UNIT I

INTRODUCTION
Concept of Species
BIODIVERSITY

Species are often defined as a group of individuals with

Biodiversity refers to the variety of plants and animals found on earth. It measures the
similar characteristics, where they can interbreed to produce
variations at ecosystem, species and genetic levels. Biodiversity conservation is the
fertile offsprings. “ To differentiate between different types of
protection and management of biodiversity to obtain resources for sustainable development.
living organisms, species is used as the principal natural unit
in biology. Species diversity is defined as the number of
Significance of biodiversity
different species present in an ecosystem and relative
abundance of each of those species”. The word „Species‟ has
1. Biodiversity protects the fresh air, clean water and productive land.
been derived from the Latin word meaning „appearance‟ or „
2. It is also important for forestry, fisheries and agriculture, which depend on rich water
kind‟.
variety of various biological resources available in nature.
 Linnaeus described species in terms of morphology.
3. Loss of biodiversity exerts heavy economic and social costs for any country.
Modern taxonomists put several changes on the basic
4. It is very important for human life; we depend on plants, microorganisms and earth’s
concept of species by considering several factors like
animals for our food, medicine and industrial products.
genetic as well as behavioral differences while
describing species.
Biodiversity conservation has three main objectives:
 Species is a natural population of individuals or group
of population which resembles one another in all
 To preserve the diversity of species.
essential morphological and also reproductive characters.
 Sustainable utilization of species and ecosystem.
 They are able to interbreed freely and produce fertile progenies.
 Maintaining life-supporting and essential ecological processes.
 Diversity is greatest when all the species present are equally abundant in the area.
The variability and diversity of living organisms and the surroundings in which they live are
known as biodiversity.
Types of Species
The three components of biodiversity are There are different types of species that exist on this earth. However, they are broadly
categorized into six concepts; these are –
1. Ecosystem diversity - It is a composite degree of diversity, which signifies a broad
array of ecosystems, ecological processes, and biotic communities in the biosphere. 1. Biological Species Concept
Examples are the desert, mangroves, etc.
2. Species diversity- The number of distinct species found at a place is the most In 1940, zoologist Mayr presented a widely accepted quotation of biological concepts. It was,
common degree of diversity. “groups of actually or potentially interbreeding natural populations which are reproductively
Examples are humans, bird species, plant species, etc,. isolated from other such groups”.
3. Genetic diversity- It signifies the diversity possessed by a single species at the This theory explains that organisms distinct at a biological level do not interbreed with each
genetic level. other when budding in the same region. According to Mayr, species of these groups has
Examples are Different breeds of dogs, different varieties of rose flower, wheat, rice, specific characteristics, these are –
mangoes,
The term biodiversity was first coined by W.G. Rosen in the year 1980. It is a shortened  Ecological Unit:
combination of two words “biological” and “diversity”. Biodiversity or biological diversity is Even though the members of a species are different from each other, they form a
often defined because of the vast diversity of species and sorts of all the life forms existing on group together. They interact with other members of the species in any environment.
earth. They include the species of microorganisms, algae, fungi, plants, animals, occurring on
 Reproductive Community:
the earth in various habitats and the ecological complexes and niches of which they are apart.
Approximately 45,000 species of plants and nearly twice as many species of animals are
found in India.
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 The members form a reproductive community and seek a partner within that group for This concept classifies species in a particular group according to its ancestors. It claims that
reproduction. every individual within a species shares a certain resemblance with its lineage. However, this
concept has a flaw. It is not easy to reconstruct an evolutionary pathway, even if so, it is not
 Genetical Unit: satisfactory all the time.
A substantial intercommunicating gene pool exists with this group, allowing members
to freely interbred. However, the individual elements are a temporary vessel These classifications of various types of species rely on different theories developed over
containing a small portion of that gene pool. time. Similarly, like other theories, they have their flaws. Students can use the Vedantu app to
This theory has gained reputation among scientists for years due to its simplicity. However, access other methods of biology as well as other topics of
there are certain limitations of biological species concept, these are Asexual organisms do not the subject.
come under this theory. Apomictic or asexual organisms display uniparental reproduction via
apomixes, parthenogenesis, budding, etc. Concept of Species

2. Nominalistic Species Concept Species form the basic manner by which biological
organisms are classified. They are large broad sections of
This concept deals with the idea of individuals.
organisms, where two similar entities belonging to the
The promoters of this theory believed that in nature, only individuals exist, and not any types same species produce offspring through the process of
of species. According to them, the concept of species is human-made and has no real reproduction. Within the classification modes, there are
existence in nature.
karyotypes, morphology, DNA sequences, etc. which help
specify and narrow down various biological organisms in a
Moreover, they regarded it as a mental concept. This concept was popular during the 18th species. This article discusses the imminent extinction of
century and still has some followers in the world of botany. various species and the impact it shall have on global
biodiversity.
3. Typological Species Concept

According to this concept, several diversities exist on earth, but in limited variations. There are two constituents of species
Moreover, they do not have any relationship between them. In this concept, these universals diversity:
 Species richness: Number of different species present in an ecosystem. Tropical areas
are called species. However, it is irrelevant to consider variations in this topic.
have greater species richness as the environment is conducive for a large number of
species
4. Evolutionary Species Concept
 Species evenness: Relative abundance of individuals of each of those species. If the
To describe this species concept, Wiley in 1981 said evolutionary species “is a single lineage number of individuals within a species is fairly constant across communities, it is said
of ancestor-descendant populations of organisms which maintains its identity from other such to have a high evenness and if the number of individuals varies from species to
lineages in space and time and which has its evolutionary tendencies and historical fate”. species, it is said to have low evenness. High evenness leads to greater specific
diversity.
Moreover, to include the species not considered under the biological species concept, this
process was formed. Variation :

5. Ecological Species Concept The concept of variation in plants encompasses the differences observed among individuals
within a plant species and how these differences contribute to adaptation, evolution, and
This concept studies ecological competition in an ecosystem. In simpler words, two similar biodiversity. Variation in plants can be categorized into several types, each with its
implications for plant biology and ecology.
categories of species have the same requirements; thus, their needs are likely to overlap. In a
situation like this, they compete with each other for a particular resource. Types of Variation in Plants

6. Phylogenetic Species Concept 1. Genetic Variation:

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 Definition: Genetic variation refers to differences in the DNA sequences among  Leaf Characteristics: Leaves may vary in size, shape, and color
individuals of the same plant species. This variation is crucial for evolutionary depending on factors such as water availability, light intensity, and
processes and adaptation. temperature.
 Sources:
 Interaction with Genetics: Environmental factors can interact with genetic
 Mutations: Random changes in DNA that create new genetic variants. predispositions to affect how traits are expressed. For example, a plant with a genetic
For example, a mutation might result in a new flower color. potential for large leaves might only develop them in optimal conditions.
 Recombination: During sexual reproduction, genetic material is
shuffled, leading to new combinations of genes in offspring. 4. Geographic Variation:
 Gene Flow: The movement of genes between populations through
processes like pollination and seed dispersal.  Definition: Differences in traits among plant populations that are geographically
separated. These differences often arise due to adaptation to different environmental
 Importance: Provides the raw material for natural selection. Populations with higher conditions.
genetic variation are better equipped to adapt to changing environments and resist  Examples:
diseases.
 Size and Shape: Plants from different regions might show variations
2. Phenotypic Variation: in size or shape based on local climate and soil conditions.
 Adaptations: Variations in drought tolerance or cold resistance among
 Definition: Phenotypic variation includes differences in observable traits among populations from different climatic regions.
plants, such as leaf shape, flower color, and plant height. These traits result from the
interaction between genetic makeup and environmental factors.  Relevance: Geographic variation helps plants adapt to diverse environments and can
 Types: lead to the formation of different ecotypes or subspecies.

 Continuous Variation: Traits that show a range of values rather than 5. Intraspecific Variation:
distinct categories (e.g., plant height, leaf size). These traits are often
influenced by multiple genes and environmental factors.  Definition: Variation within a single species, including differences among individuals
 Discrete Variation: Traits that fall into distinct categories (e.g., flower within a population or among populations of the same species.
color, presence or absence of certain leaf structures). These traits are  Relevance: Studying intraspecific variation is important for understanding adaptation,
usually controlled by a small number of genes. genetic diversity, and the impact of environmental changes on populations. It also
informs conservation efforts by highlighting the need to preserve genetic diversity
 Influences: Both genetic factors and environmental conditions influence phenotypic within species.
traits. For instance, the size of a plant might vary depending on soil nutrients and
water availability. Importance of Variation in Plants

3. Environmental Variation: 1. Adaptation and Evolution:

 Definition: Variation in traits due to differences in environmental conditions rather  Adaptation: Variation allows plant populations to adapt to environmental changes,
than genetic differences. Plants may exhibit different characteristics based on their such as shifts in climate or soil conditions. Plants with beneficial traits are more likely
environment. to survive and reproduce.
 Examples:  Evolution: Genetic variation is essential for evolution. It provides the diversity
needed for natural selection to act upon, leading to the evolution of new traits and
 Growth Form: A plant’s growth form (e.g., tall or short) can vary species over time.
with changes in light availability or soil fertility.
2. Ecological Interactions:

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  Interactions: Variation in plant traits can influence interactions with other organisms,  Mosses: These small, green, carpet-like plants are found in various habitats, including
such as pollinators, herbivores, and competitors. For example, variations in flower forests, wetlands, and even urban areas. Mosses play a crucial role in ecosystems by
color can affect pollinator attraction. preventing soil erosion and retaining moisture.
 Liverworts: Liverworts come in two main forms: leafy and thalloid. Leafy liverworts
3. Conservation: resemble mosses but with differently structured leaves, while thalloid liverworts have
a flat, ribbon-like appearance. They are often found in damp, shaded environments.
 Genetic Diversity: Maintaining genetic variation is crucial for the long-term survival  Hornworts: Named for their horn-shaped sporophytes, hornworts are less common
of plant species. It helps populations adapt to changing conditions and reduces the risk than mosses and liverworts. Their sporophytes grow from a basal meristem and can
of extinction. appear horn-like or cylindrical.
 Management: Understanding variation within species aids in developing effective
conservation strategies, including habitat management and breeding programs. 2. Pteridophytes

4. Agriculture and Horticulture: Pteridophytes are vascular plants that reproduce via spores
instead of seeds. They possess vascular tissues (xylem and
 Crop Improvement: Variation in agricultural plants is harnessed to improve crop phloem) for transporting water and nutrients. Major groups
traits, such as yield, disease resistance, and stress tolerance. Breeding programs include:
often rely on genetic variation to develop new cultivars with desirable
characteristics.  Ferns: These plants have feathery, divided leaves called fronds. Spores are produced
in structures called sori on the underside of the fronds. Ferns are commonly found in
Introduction to Major Plant Groups tropical and temperate rainforests.
 Clubmosses: Often mistaken for mosses, clubmosses are small, evergreen plants with
needle-like leaves. They are typically found in forested areas and have a distinctive
appearance due to their scale-like leaves.
 Horsetails: Characterized by their jointed, hollow stems and tiny leaves, horsetails
are ancient plants that thrive in wet environments. They have a unique appearance
with a segmented, almost bamboo-like structure.

3. Gymnosperms

Gymnosperms are seed-producing plants that do not produce

Bryophytes Pteridophytes Gymnosperms Angiosperms
flowers. Their seeds are often exposed on cones or other structures.
There are four major groups of plants Major groups include:

Plants are an incredibly diverse group of organisms, and they can be broadly categorized into  Conifers: This group includes cone-bearing trees and shrubs such as pines, spruces,
several major groups based on their characteristics and evolutionary history. Here’s a brief and firs. Conifers have needle-like leaves and are adapted to a variety of climates,
introduction to the major plant groups: often dominating cold and temperate forests.
 Cycads: Cycads have a palm-like appearance with large, compound leaves and
1. Bryophytes produce seeds in cones. They are ancient plants that were more common in the
Mesozoic era and are now mostly found in tropical and subtropical regions.
Bryophytes are non-vascular plants, meaning they lack the  Ginkgoes: The Ginkgo biloba is the only surviving species of this group. It is known
specialized tissues (xylem and phloem) used for transporting water for its distinctive fan-shaped leaves and is often planted as an ornamental tree.
and nutrients. They are typically small and grow in moist Ginkgoes are considered living fossils due to their ancient lineage.
environments. There are three main groups within bryophytes:

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  Gnetophytes: This diverse group includes plants like Ephedra (with jointed stems) 1. Terrestrial Plants
and Gnetum (with broad leaves). Gnetophytes exhibit a range of forms and
adaptations, and some are used in traditional medicine These plants grow on land and are adapted to a wide range of terrestrial environments.

4. Angiosperms  Forest Plants: Include trees, shrubs, and understory plants found in tropical,
temperate, and boreal forests. Examples are oak trees, ferns, and mosses. These plants
Angiosperms, or flowering plants, are the most diverse and are adapted to various light levels and soil types.
widespread plant group. They produce flowers and seeds  Grassland Plants: Found in areas with moderate to low rainfall, such as prairies and
enclosed within fruits. They are divided into two main classes: savannas. Examples include grasses like bluestem and plants like sunflowers and
wildflowers. They are adapted to withstand periodic droughts and fires.
 Monocots: Characterized by having one seed leaf  Desert Plants: Adapted to arid conditions with minimal water. Examples include
(cotyledon), parallel leaf veins, and flower parts in cacti, succulents, and xerophytes like sagebrush. These plants have specialized
multiples of three. Examples include grasses, lilies, and adaptations like water storage tissues and reduced leaf surfaces.
orchids.  Mountain Plants: Thrive in high-altitude
 Dicots: Have two seed leaves, net-like leaf veins, and environments with cooler temperatures and
flower parts in multiples of four or five. Examples variable conditions. Examples include alpine
include roses, sunflowers, and oaks. meadows and plants like edelweiss and
cushion plants. They are adapted to extreme
Comparison of Structural Characteristics of Monocots and Eudicots weather and short growing seasons.

Characteristic Monocot Eudicot 2. Aquatic Plants

Cotyledon One Two
Veins in leaves Parallel Network ( branched) These plants live in water environments and are adapted to varying degrees of submersion.
Vascular tissue Scattered Arranged in ring pattern
Network of adventitious Tap root with many lateral  Floating Plants: These plants float on the water's
Roots
roots roots
Pollen Monosulcate Trisulcate surface and include species like water lilies and
Four, five, multiple of four duckweed. They have adaptations for buoyancy
Flower parts Three or multiple of three and gas exchange.
or five and whorls
 Submerged Plants: Grow completely
underwater and include species like eelgrass and
pondweed. These plants are adapted to low light
Angiosperms range from small herbs to large trees and dominate terrestrial ecosystems conditions and have structures for absorbing
worldwide. They include monocots (like grasses and lilies) and dicots (like roses and oaks). nutrients directly from the water.
Eg: mango, apple, banana, peach, rice, corn, wheat, etc,.  Emergent Plants: Grow with their roots
submerged in water but with stems and leaves
These groups reflect the evolutionary history and adaptations of plants to different extending above the surface. Examples include
environments. Each group has its own unique characteristics and ecological roles, cattails and bulrushes. They are adapted to
contributing to the rich diversity of plant life on Earth. fluctuating water levels and have structures to
stabilize them in water.
Plants can be categorized into different groups based on their habitats or the
environments : 3. Epiphytes

These habitat-based classifications help in understanding the ecological roles and adaptations Epiphytes grow on other plants (usually trees) but do not parasitize them. They derive
of various plant types. Here are some of the main plant groups according to their habitats: moisture and nutrients from the air, rain, or debris accumulating around them.

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  Orchids: Many orchids are epiphytes, with their roots adapted to absorb moisture  Green Algae: The earliest ancestors of land plants were green algae, which existed in
from the air and organic matter. aquatic environments around 450-500 million years ago. These algae began adapting
 Ferns: Some ferns, such as staghorn ferns, are to terrestrial environments, leading to the evolution of the first land plants.
epiphytic and thrive on tree branches or other surfaces.  Bryophytes (Non-Vascular Plants): Bryophytes, including mosses, liverworts, and
 Air Plants (Tillandsia): These are a type of epiphyte hornworts, are among the earliest land plants. They lack vascular tissues (xylem and
with specialized structures to capture moisture from phloem) and are adapted to moist environments. Bryophytes represent an early stage
the air. in plant evolution, marking the transition from aquatic to terrestrial life.

4. Halophytes 2. Emergence of Vascular Plants

Halophytes are plants adapted to high-salinity environments, such as salt marshes and coastal Pteridophytes:
areas.
 Evolution of Vascular Tissues: Around 400-350 million years ago, plants evolved
 Mangroves: These trees and shrubs grow in coastal vascular tissues, which include xylem for water transport and phloem for nutrient
intertidal zones and are adapted to saltwater conditions. transport. This development allowed plants to grow larger and more complex.
Examples include the red mangrove and black mangrove.  Pteridophytes: This group includes ferns, clubmosses, and horsetails. They have
 Saltbushes: These plants, like the Australian saltbush, can vascular tissues and reproduce via spores but do not produce seeds. Pteridophytes are
tolerate high salt concentrations in the soil. more advanced than bryophytes due to their vascular systems but less complex than
seed plants.
5. Carnivorous Plants
3. Evolution of Seed Plants
Carnivorous plants have evolved to capture and digest insects and
other small animals to obtain nutrients from their prey. Gymnosperms:

 Venus Flytrap: Uses modified leaves that snap shut to trap  Development of Seeds: Around 350-300 million years ago, seed plants evolved.
insects. Seeds provide a protective covering for the embryo and a food source, facilitating the
 Pitcher Plants: Have tubular, pitcher-shaped leaves that colonization of diverse environments.
trap and digest insects.  Gymnosperms: This group includes conifers, cycads, ginkgoes, and gnetophytes.
 Sundews: Feature glandular hairs that secrete a sticky Gymnosperms produce seeds that are not enclosed in fruits and are a major branch of
substance to capture prey. seed plants. They represent an important evolutionary step from spore-producing
plants.
Each of these plant groups has evolved specialized adaptations to
thrive in their specific habitats, showcasing the incredible Angiosperms (Flowering Plants):
diversity of plant life and their ability to colonize various
environments.  Evolution of Flowers and Fruits: Angiosperms appeared around 140-200 million
years ago. They are characterized by the development of flowers and seeds enclosed
Evolutionary relationships between Plant Groups within fruits, enhancing reproductive efficiency and diversity.
 Angiosperms: The most diverse and widespread group of plants, angiosperms include
The evolutionary relationships among plant groups are elucidated through the study of their monocots (e.g., grasses, lilies) and dicots (e.g., roses, oaks). The evolution of flowers
shared ancestry and evolutionary developments. Here’s a detailed summary of how major and fruits allowed for more efficient pollination and seed dispersal, contributing to
plant groups are related through their evolutionary history: their ecological success.

1. Early Plant Evolution 4. Phylogenetic Relationships

Algae to Bryophytes: a. Bryophytes

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  Description: Bryophytes represent the earliest branch of the plant phylogenetic tree.  Dicots: Plants with two seed leaves and often net-veined leaves
This group includes mosses, liverworts, and hornworts. (e.g., roses, oaks).
 Key Features:
o Non-Vascular: Lacking xylem and phloem, which means they do not have Phylogenetic Tree
specialized tissues for transporting water and nutrients.
o Adaptation: Generally adapted to moist environments, as they rely on The phylogenetic tree of plants illustrates the evolutionary relationships among these major
diffusion for water and nutrient uptake. groups:
o Reproduction: Reproduce via spores, with a life cycle dominated by the
gametophyte stage. 1. Bryophytes form the most primitive branch, representing early land plants that
transitioned from aquatic environments to terrestrial habitats.
b. Pteridophytes 2. Pteridophytes represent a significant evolutionary step with the development of
vascular tissues, allowing plants to grow larger and more complex.
 Description: Pteridophytes are the first vascular plants and include ferns, clubmosses, 3. Seed Plants further evolved from pteridophytes, with the development of seeds
and horsetails. providing protection and nourishment for the developing embryo. This branch divides
 Key Features: into:
o Vascular Tissues: Possess xylem and phloem for efficient water and nutrient o Gymnosperms: Seed plants with exposed seeds, which were dominant before
transport, allowing for greater size and complexity compared to bryophytes. the evolution of flowering plants.
o Reproduction: Reproduce via spores rather than seeds, and their life cycle is o Angiosperms: The most advanced and diverse group of seed plants,
characterized by a dominant sporophyte stage. characterized by flowers and fruits that enhance reproductive efficiency and
seed dispersal.
c. Seed Plants
This tree provides a framework for understanding how plants have evolved various
Seed plants are a major evolutionary group that can be divided into two primary categories: adaptations to survive and thrive in different environments over millions of years.

 Gymnosperms 5. Key Evolutionary Innovations

o Description: Gymnosperms are seed plants with exposed seeds. This group
includes conifers (pines, spruces), cycads, ginkgoes, and gnetophytes. Vascular Tissues: The development of xylem and phloem allowed for greater plant height
o Key Features: and efficient nutrient transport. This innovation is seen in pteridophytes and all seed plants.
 Seeds: Seeds are not enclosed within fruits; instead, they are often
found in cones or other structures. Seeds: The evolution of seeds provided protection and nourishment for the embryo, leading
 Reproduction: Reproduction occurs through cones or similar to the rise of gymnosperms and angiosperms.
structures, with no flowers involved.
 Angiosperms Flowers and Fruits: The development of flowers and fruits in angiosperms enhanced
o Description: Angiosperms are seed plants that produce flowers and fruits. reproductive success and diversity, facilitating more effective pollination and seed dispersal.
They are the most diverse and widespread group of plants.
o Key Features: An example of a homologous structure in plants is the leaf.
 Flowers: Facilitate pollination by attracting pollinators, which Groups of vascular plants have evolved from a shared
enhances reproductive success. common ancestor that formed leaves. In particular, we could
 Fruits: Enclose the seeds, aiding in seed dispersal. This adaptation look at leaves formed by flowering plants (Angiosperms),
allows for a wide range of seed dispersal methods. the most recent major clade within kingdom Plantae. The
 Classification: Angiosperms are further divided into two main groups: developmental pathway and internal anatomy of these leaves
 Monocots: Plants with one seed leaf (cotyledon) and parallel- have similarities due to shared ancestry, though they may
veined leaves (e.g., grasses, lilies). appear outwardly different.

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The evolutionary relationships among plant groups highlight a progression from simple, non-  Purpose: Governs the rules for naming plants, algae, and fungi to ensure consistency
vascular plants to more complex vascular and seed-bearing plants. Key innovations such as and clarity in botanical nomenclature.
vascular tissues, seeds, and flowers enabled plants to adapt to various environments and  Current Version: The Melbourne Code, established in 2011, is the most recent
become dominant terrestrial organisms. Understanding these relationships provides insights version. It includes updates and revisions to address new developments in taxonomy.
into the diversity and evolutionary history of the plant kingdom.
Key Principles:
Nomenclature and History of plant taxonomy
 Principle of Priority: The earliest validly published name for a species takes
Nomenclature of plant taxonomy precedence. This ensures stability in naming, even as taxonomic understanding
evolves.
 Principle of Type: Each plant name must be associated with a type specimen, which
serves as the definitive reference for the species' identity.
 Principle of Binomial Nomenclature: Each species must be given a unique two-part
Plant taxonomy and nomenclature are fundamental to the study of plants. They provide the
framework for naming, classifying, and understanding plant diversity. Here's a more name, adhering to the binomial system.
elaborate look at the principles, rules, and recent developments in plant nomenclature:
Structure:
1. Binomial Nomenclature
 Taxonomic Ranks: The hierarchy of names must follow a specific order:
Concept: o Family: A group of related genera.
o Genus: A group of closely related species.
 Introduction: The binomial nomenclature system was introduced by Carl Linnaeus in o Species: The basic unit of classification.
the 18th century through his work "Species Plantarum" (1753).  Publication: Names must be published in a scientific journal or book that is publicly
 Format: Each species is named with a two-part Latin name: accessible and includes a description or diagnosis of the plant.

Genus Name: Identifies the group of closely related species. It is always 3. Taxonomic Ranks
capitalized (e.g., Rosa).
Species Epithet: Distinguishes the species within the genus. It is always in Hierarchy:
lowercase (e.g., rubiginosa).
Example: Rosa rubiginosa (the sweet briar rose). 1. Domain: The highest rank,
such as Eukarya.
Purpose: 2. Kingdom: Major groups
like Plantae (plants).
 Standardization: Ensures that each plant species has a unique and universally 3. Phylum (or Division for
accepted name, reducing confusion that arises from local or common names. plants): Major groups
 Communication: Facilitates accurate communication among botanists, researchers, within a kingdom, like
and horticulturists globally. Angiosperms.
4. Class: Subdivisions within a phylum, like Magnoliopsida (dicotyledons).
Rules: 5. Order: Groups of related families, such as Rosales.
6. Family: Groups of related genera, such as Rosaceae (the rose family).
 Italicization: Both parts of the name are italicized or underlined when handwritten to 7. Genus: Groups of related species, such as Rosa.
indicate their Latin origin (e.g., Rosa rubiginosa). 8. Species: The fundamental unit of classification, like Rosa rubiginosa.
 Uniqueness: Each name must be unique to avoid ambiguity in identification.
♠ Kingdom
2. International Code of Nomenclature for algae, fungi, and plants (ICN)

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The kingdom is the highest level of classification, which is divided into subgroups at various  Type Specimen: A physical specimen of a plant that serves as the reference for the
levels. There are 5 kingdoms in which the living organisms are classified, namely, Animalia, species name.
Plantae, Fungi, Protista, and Monera.
Purpose:
♠ Phylum
 Reference: Provides a concrete reference for the identity of the species.
This is the next level of classification and is more specific than the kingdom. There are 35  Stability: Ensures that the name of a species remains consistent over time.
phyla in kingdom Animalia. For Example – Porifera, Chordata, Arthropoda, etc.
Types:
♠ Class
Class was the most general rank in the taxonomic hierarchy until phyla were not introduced.  Holotype: The single specimen designated as the type when the species is described.
Kingdom Animalia includes 108 classes including class mammalia, reptilia, aves, etc. It serves as the primary reference.
However, the classes used today are different from those proposed by Linnaeus and are not  Isotype: Duplicate specimens of the holotype collected at the same time and place,
used frequently. used for verification and reference.
 Paratype: Additional specimens cited in the original description but not the holotype.
♠ Order These help illustrate variability within the species.

Order is a more specific rank than class. The order constitutes one or more than one similar 5. Rules for Naming
families. There are around 26 orders in class mammalia such as primates, carnivora, etc.
Publication:
♠ Family
 Requirements: Names must be published in a recognized scientific medium, such as
This category of taxonomic hierarchy includes various genera that share a few similarities.
a peer-reviewed journal or botanical monograph, with a detailed description or
For eg., the families in the order Carnivora include Canidae, Felidae, Ursidae, etc.
diagnosis of the plant.

♠ Genus Validity:
A group of similar species forms a genus. Some genera have only one species and is known
as monotypic, whereas, some have more than one species and is known as polytypic. For eg.,  ICN Compliance: Names must adhere to the rules of the ICN, including proper
lion and tiger are placed under the genus Panthera. description, publication, and association with a type specimen.

♠ Species Homonymy:

It is the lowest level of taxonomic hierarchy. There are about 8.7 million different species on  Definition: The use of the same name for different species. The same name cannot be
earth. It refers to a group of organisms that are similar in shape, form, reproductive features. used for more than one species. If a name is already in use, a new name must be
Species can be further divided into sub-species. chosen.

Additional Ranks: Synonymy:

 Subspecies: Variants within a species that are geographically or ecologically distinct.  Definition: Different names that refer to the same species. Synonyms arise when
 Variety: Differences within a species that are less distinct than subspecies. species are reclassified or renamed, and different taxonomists use different names for
 Form: Minor variations within a variety or species, often related to morphology. the same plant.

4. Type Specimens 6. Recent Developments

Definition: Molecular Phylogenetics:

17 18
  Genetic Analysis: The use of DNA sequencing and molecular data has revolutionized Theophrastus (370-285 B.C.):
plant taxonomy by clarifying evolutionary relationships and leading to revisions in
classification.  History of plant classification dates back to the period of
 Impact: Molecular techniques can reveal cryptic species and reclassify plants based Theophrastus, who is also known as the father of botany.
on genetic evidence rather than just morphological characteristics.  He was pupil of the great Greek philosopher Aristotle.
Theophrastus was a Greek naturalist, described 480 plants in his
Electronic Publishing: book HistoriaPlantarum.
 He classified plants for convenience into four groups
 Advancements: Online databases and journals facilitate the rapid publication and namely, herbs, undershrubs, shrubs and trees.
dissemination of new plant names and taxonomic updates.  Small, delicate plants were grouped under herbs, smaller size bushy woody plants
 Access: Provides easier access to taxonomic information and databases for were brought under undershrubs and shrubs depending on their relative sizes and
researchers worldwide. large woody plants with main stem with branches at the top were grouped under trees.
 He pointed out the fundamental differences between Dicotyledons and
Global Databases: monocotyledons.

 Plant List: An extensive database of plant names, including accepted names and PeanionDioscorides (62-128 A.D.) – He explained about 600 plants of medicinal
synonyms. importance.He recorded his work in his book “ MateriaMedica “ in Greek language
 World Flora Online: A global initiative to provide comprehensive information on
plant species and their distributions. Albertus Magnus (1193-1280) - He recognized the difference between the Dicotyledons and
 Global Biodiversity Information Facility (GBIF): Provides access to a vast monocotyledon plants. He described plants and practical methods of gardening in his book
repository of biodiversity data, including plant taxonomy. “Devegetabilis”.His work was followed till the next 200 years not only by the botanists, but
also by the common people due to its practicability.
Plant nomenclature is dynamic and continuously evolving as new discoveries are made and
taxonomic practices are refined. This system ensures that plant names are precise, consistent, Otto Brunfels (1464-1534) - He was a German teacher and physician and was one of the first
and useful for scientific communication. group of herbalists who gave a consolidated account of plants, known at that time .He was
interested in the medicinal values of plants and their domestic uses. He first recognised the
History of plant taxonomy
Perfecti and Imperfecti group of plants based on the presence and absence of flowers
respectively.
Taxonomy is the science which deals with the study, identification, nomenclature and
systematic arrangement of living organisms. When the study is related to plants, it is called
Jerome Bock (1498-1554) - A German school teacher, then a minister and a physician was
plant taxonomy. Similarly animal taxonomy deals with the classification of animals. The
interested in plants and studied botany only as a hobby. He classified plants into trees, shrubs
word taxonomy has its origin from the Greek word taxis meaning arrangement; nomous
and herbs and tried to bring plants of similar habits and affinities together. He is also known
means name. Hence, the plant taxonomy may be defined as the study of principles and
as the second of the “German Fathers of Botany “
practices of classification of plants and their relationships. History of plant taxonomy is
divided into different periods on the basis of the principles adopted during the periods. Andrea Caesalpino (1519-1603)- He was an Italian physician and a botanist. He authored a
book “ DePlantis “ (1583). There was description of over 1500 plant species, which were
Period I
classified under two major groups- woody and herbaceous habit. He also recognised the
characters of fruit, seed and embryo in his groups. J.
Classification based on habit :
Bauhin (1541-1613)- French physician who wrote “HistoriaPlantarumUniversalis”, which
 Such systems of classification were associated with the beginning of the taxonomy.
was published posthumously in 1650-51 in 3 volumes.
 These were prevalent from 300 B.C. to almost the middle of the eighteenth century.
 Such systems were propounded by the Greek herbalists and botanists and were based G. Bauhin (1560-1624)- Described plants in his twelve books “ProdromusTheatriBotanici
on habit of plants. (1620) and PinaxTheatriBotanici (1623)”. The Pinax consisted of description of about 6000
 They were only crude systems, but were in practice and accepted ones. plant species.He was the first person to find out the binomial nomenclature although it is

19 20
credited to a Swedish botanist Carolus Linnaeus, who brought it into practice in his Species  He published a number of papers such as Genera Plantarum, Flora lapponica, Species
plantarum. Plantarum etc.
 In which he has described all the plant species known that time.
John Ray (1628-1705)- A British naturalist recognised two major groups in angiosperms on  Besides all this, Linnaeus proposed what is known as the sexual system of
the basis of habit and other morphological and few anatomical characters.He wrote the book classification.
” HistoriaPlantarum “ . His broad classification was as follows :  In his system all plants including lower plants were divided into 24 classes on the
basis of number, union, length, and certain obvious characters of the stamens.
A. Herbae --Herbaceous plants However, this is not fit for the lower plants which bear no flowers.
 Linnaeus’s system was artificial, but due to its simplicity and easy way for
(i) Imperfectae (Flowerless plants) identification of plants, it persisted for nearly hundred years in spite of many
shortcomings.
(ii) Perfectae (Flowering plants)
 He was fully aware of its shortcomings and he considered it as a makeshift
arrangement to deal with a large number of plants. He is regarded as a reformer in the
(a) Dicotyledones (seed with two cotyledons)
field of taxonomy.
(b) Monocotyledones (seed with single cotyledon)  He is known as propounder of binomial system of nomenclature, which is being
followed till date.
B. Arbores—Tree habit  He introduced the precision to the art of description and nomenclature of species.
 By 1760 his system was adopted widely in the European countries namely Germany,
(i) Dicotyledones Holland and England.

(ii) Monocotyledones
Systems of Classification and their Application;
J.P. Tournefort (1656-1708)- Published Elements de Botanique in 1694, which was
translated into in Latin and published in the year 1700 in three volumes. He is called as the Introduction:
founder of modern genera. He took floral characters in consideration for the purpose of  Biological classification is a scientific method that involves grouping organisms into a
classification, besides habit. However, his classification lacked distinction in Phanerogams hierarchical series of groups and subgroups based on their similarities and differences.
and Cryptogams and also between monocots and dicots.  Three types of systems of classification have been recognized-
(1) Artificial (2) Natural (3) Phylogenetic
Period II

Artificial systems based on numerical classification

These systems were designed to help in identification of plants. Since, there was very least
knowledge of characters of plants and the systematists did not follow the classification of
form that was prevalent since the time of Aristotle. A new classification was proposed by a
Swedish botanist Carolus Linnaeus, whose classification gained popularity at that period

Carolus Linnaeus (1707-1778) –

 He is still widely known botanist of modern times. He was (1) Artificial system of classification
 In an artificial system of classification gross, superficial and morphological
a Swedish physician, professor of practical medicine as well as a
botanist . characteristics are taken into account for classification.
 Vegetative (habit, number ,shape and colour of the leaf) and sexual characters (structure
 He is also known as the father of taxonomic botany and
zoology. of androecium) give equal importance which is not acceptable as vegetative characters
are more easily effected by the environment.

21 22
 Some of the important contributions are discussed as follows-  Lack of Evolutionary Context: Does not reflect evolutionary relationships or genetic
a. Aristotle: connections between plants. The classification is based on superficial or arbitrary
i. He used simple morphological characters to classify plants into herbs, shrubs and trees. characteristics.
ii. He classified animals into Anaima and Enaima, on the basis of absence and presence of  Limited Insight: May group unrelated plants together or separate closely related
RBCs respectively. plants based on traits that do not indicate evolutionary relationships.
 Static Nature: Does not adapt well to new discoveries or insights into plant evolution
and relationships.

Example: Linnaeus's original classification system, which focused on the number and
arrangement of reproductive organs.

(2) The natural system of classification

 It is based on the affinities between organisms
 It takes into account not only external but internal features like ultrastructure, anatomy,
embryology, and phytochemistry for classification.
 George Bentham and Joseph Dalton Hooker, both of whom were closely involved with

b. Theophrastus, the inventor of botany, divided plants into four categories based on their
the Royal Botanic Garden at Kew, England, proposed a natural system of classification of
habit: angiosperms that was published in ‘Genera Plantarum’ in 3 volumes.
 They classified the plant kingdom into two subkingdoms–Cryptogamia and
- Herbs
Phanerogamia.
- UnderShrubs
 The phanerogamia are classified into three classes–Dicotyledons, Gymnosperms and
- Shrubs
Monocotyledons.
- Trees
i. "Enquiry into plants" (also known as HistoriaPlantarum) and "Causes of plants" are his two The advantages of Bentham's and Hooker's systems are as follows:
writings on plants. (i) It is practically important, as most of the herbaria of the world are based on this system of
classification.
ii. He wrote about almost 500 distinct plant species, naming them by the names that were (ii) They placed Ranales (most primitive) in the beginning of classification that is
popular at the time. phylogenetically true.
(iii) They placed monocots after dicots which is similar to phylogenetic systems.
c. Carl Linnaeus proposed an artificial system of classificationon the basis of few sexual
characters like on the androecium structure (number of stamens), in his book Genera Demerits of Bentham's and Hooker's classification systems
Plantarum. He classified plants into 24 classes. Out of them, 23 were of phanerogams and
(i) They did not use phylogenetic trends in their classification.
24th class was of cryptogams.
(ii) Gymnosperms are placed between dicots and monocots which is not
Merits:
acceptable.Monochlamydeae is placed after gamopetalae which does not
 Simplicity: Easy to apply and understand, often using a limited number of traits that seem to be natural.
are straightforward to observe.
 Practicality: Useful for quick identification and organization of plants, particularly in (iii) Some of the associated orders are geographically isolated.
fields like horticulture and agriculture where specific traits are of primary interest. Groups are not arranged in a consistent manner.
 Historical Value: Paved the way for more sophisticated classification systems and
helped in the early development of botanical taxonomy.

Demerits:

23 24
 Merits:

 Accurate Evolutionary Relationships: Provides a precise depiction of plant

relationships based on evolutionary history and genetic data. This system reflects the
true evolutionary connections among plants.
 Data-Driven: Utilizes modern techniques such as DNA sequencing and phylogenetic
analysis, leading to highly accurate and objective classifications.
 Dynamic: Can be updated with new genetic information, allowing for continuous
refinement and revision of plant classifications.

Demerits:

 Technical Complexity: Requires advanced technical skills and access to

sophisticated tools and methods, such as genetic sequencing technologies.
 Cost: Molecular and genomic studies can be expensive and resource-intensive, which
may limit their application in some contexts.
 Potential for Revision: Frequent updates and revisions based on new genetic data can
lead to changes in classification that may be confusing or challenging to keep up with.

Phylogenetic Classification (Cladistics): Example: The Angiosperm Phylogeny Group (APG) system, which uses genetic data to
 Evolutionary history of the organism is called Phylogeny. classify flowering plants and has undergone multiple revisions based on new research.
 These systems are based on Phylogenetic relationships of organisms.
 Phylogenetic systems are also called Cladistics (Systematic classification based on
evolutionary relationships of organisms in order of their assumed divergence from
ancestral forms) and the graphic representation of evolutionary relationships is called
family tree or Cladogram.
 Engler and Prantl proposed the phylogenetic classification and published it in their book
“Die NatürlichenPflanzenfamilien” in 23 volumes.
 Engler and Prantl divided plant kingdom into two sub kingdom (1) Cryptogamia:
invisible sex organs e.g. Thallophyta, Bryophyta and Pteridophyta.; (2) Phanerogamia:
visible sex organs e.g. Gymnosperm and Angiosperm.
 Later on, well-developed phylogenetic systems of classification were created by
Hutchinson, Tippo, Takhtajan, Robert Whitaker, Robert Thorne and Cronquist. Taxonomy VS systematics
 Oswald Tippo proposed the biggest phylogenetic classification of the plant kingdom and Taxonomy and systematics are two concepts that are used to identify and describe organisms.
it is most accepted for books and study. In Greek terminology, the word taxonomy means ‘putting in order’ whereas systematics
 Fossil records are the most important evidence in systematics but if fossil records are not means ‘putting together’. According to Radford (1986) systematics is the study of phonetic,
available then other branches of taxonomy like cytotaxonomy, numerical, genetic and phylogenetic relationship among taxa. Kazlev (2002) defined systematics as ‘the
chemotaxonomy etc. play important roles to find out phylogeny. branch of biology that deals with classifying living beings: the diversity and interrelationships
of living beings, both present day organisms (“neontology”) and prehistoric ones
(“palaeontology”)’, and divided the concept into three subdisciplines; phylogenetics,
taxonomy and classification

25 26
Study of Plant Groups  Division/Phylum
 Class
The study of plant groups, or plant taxonomy, involves the classification and organization of  Order
plants into various categories based on their characteristics, evolutionary history, and  Family
relationships. Here are some key aspects of plant groups:  Genus
 Species
1. Kingdom Plantae

 Division/Phylum: The primary divisions within the plant kingdom are based on
major evolutionary lines.
o Bryophytes: Non-vascular plants, including mosses, liverworts, and
hornworts.
o Pteridophytes: Vascular plants that reproduce via spores, including ferns and
horsetails.
o Gymnosperms: Seed-producing plants that do not form flowers, including
conifers, cycads, and ginkgo.
o Angiosperms: Flowering plants that produce seeds enclosed within a fruit.

2. Plant Groups

Plant groups can be categorized in various ways, often based on their taxonomy, morphology,
or ecological role. The primary groups in the plant kingdom are:
4. Plant Evolution and Adaptations
 Bryophytes: Non-vascular plants including mosses, liverworts, and hornworts. They
are simple plants that do not have true roots, stems, or leaves.  Evolutionary Trends: The evolution from non-vascular to vascular plants, and from
 Pteridophytes: Vascular plants that reproduce via spores, including ferns, horsetails, gymnosperms to angiosperms.
and clubmosses. They have true roots, stems, and leaves but no seeds.  Adaptations: Changes such as the development of seeds, flowers, and fruits that aid
 Gymnosperms: Seed-producing plants that do not form flowers. They include conifers in reproduction and survival.
(like pine trees), cycads, ginkgoes, and gnetophytes. They have naked seeds not
enclosed in fruit. 5. Applications
 Angiosperms: Flowering plants that
produce seeds enclosed within a fruit. Ecology: Understanding Plant Diversity and Distribution
They are the most diverse and widespread
group of plants and are divided into two 1. Biodiversity Assessment:
main classes: o Species Inventory: Taxonomy helps catalog and identify plant species in a

 Monocots: Plants with one given area, which is crucial for assessing the biodiversity of ecosystems.
cotyledon (e.g., grasses, lilies, o Habitat Characterization: Understanding plant groups allows ecologists to

orchids). characterize and differentiate habitats based on the plant species present.
 Dicots: Plants with two cotyledons (e.g., roses, beans, sunflowers). 2. Ecosystem Function:
o Ecological Roles: Different plant species have unique roles in their
ecosystems, such as providing food and habitat for wildlife, and influencing
soil structure and nutrient cycling.
3. Plant Classification Levels o Succession and Restoration: Knowledge of plant groups helps in
understanding ecological succession (the process of change in species
 Kingdom structure of an ecological community) and in planning restoration projects.

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 3. Climate Change Studies: Molecular Phylogenetics
o Vegetation Response: Studying plant groups helps scientists predict how
changes in climate may affect plant distributions and ecosystem dynamics. 1. DNA Sequencing:

Agriculture: Classification Aids in Cultivation and Disease Understanding  Technique: DNA sequencing technologies, such as Sanger sequencing and next-
generation sequencing (NGS), are used to analyze the genetic material of plants.
 Applications: This method provides insights into the genetic makeup of plants,
1. Crop Improvement:
revealing relationships between species, genera, and families that might not be
o Genetic Selection: Classification and understanding of plant species help in apparent from morphology alone.
selecting and breeding crops with desirable traits, such as improved yield,  Advancements: New sequencing techniques, including whole-genome sequencing
disease resistance, or drought tolerance. and targeted sequencing of specific genes, allow for more comprehensive and detailed
o Varietal Development: Knowledge of plant taxonomy aids in developing new phylogenetic analyses.
varieties that are better suited to specific environmental conditions.
2. Pest and Disease Management: 2. Phylogenetic Trees:
o Disease Identification: Understanding plant species and their relatedness
 Construction: Molecular data are used to build phylogenetic trees, which depict the
helps in diagnosing plant diseases and implementing effective management evolutionary relationships among plant species.
strategies.  Cladistics: By analyzing shared genetic traits, scientists can determine the most
o Resistance Breeding: Identifying species with natural resistance to pests and recent common ancestors and evolutionary paths.
diseases can lead to the development of resistant crop varieties.
3. Crop Rotation and Soil Health: 3. Genetic Markers:
o Rotation Practices: Taxonomic knowledge helps in designing crop rotation
 Types: Markers such as microsatellites, single nucleotide polymorphisms (SNPs), and
systems that improve soil health and reduce pest and disease pressures.
ribosomal RNA genes are used to assess genetic variation and relationships.
 Uses: These markers are helpful in studying population genetics, hybridization events,
Conservation: Identifying and Protecting Species and Habitats and genetic diversity within and between species.

1. Species Conservation: Morphological Studies

o Threat Assessment: Classification helps identify endangered or threatened
plant species and assess the factors contributing to their decline. 1. Physical Characteristics:
o Conservation Prioritization: Understanding plant diversity helps prioritize
conservation efforts and allocate resources effectively.  Examination: Morphological studies involve the detailed examination of physical
2. Habitat Preservation: traits such as leaf shape, flower structure, stem arrangement, and root types.
 Identification: Physical characteristics are used to identify and classify plants and to
o Habitat Requirements: Knowing the specific habitat needs of different plant
differentiate between species and genera.
groups aids in the protection and management of natural habitats.
o Restoration Projects: Taxonomy guides the selection of appropriate plant 2. Comparative Analysis:
species for habitat restoration projects, ensuring ecological compatibility.
3. Biodiversity Hotspots:  Traditional Methods: This includes comparing specimens from different locations or
o Identification: Taxonomic studies help identify biodiversity hotspots— time periods to understand variations and evolutionary changes.
regions with exceptionally high levels of plant species diversity that are also  Herbarium Collections: Preserved plant specimens in herbaria are analyzed for
morphological features, providing historical data on plant species.
under threat.
4. Legal and Policy Frameworks: 3. Limitations:
o Regulations: Accurate classification supports the development of legal
frameworks and policies for the protection of plant species and their habitats.  Plasticity: Morphological traits can be influenced by environmental factors, leading
to variations that may complicate classification.
6. Modern Tools and Methods  Convergence: Different plant groups may evolve similar traits independently
(convergent evolution), making it challenging to infer relationships based solely on
morphology.

29 30
Bioinformatics help in distinguishing between different plant species and groups. Here’s a detailed look at
how plant identification is approached:
1. Data Analysis:
1. Morphological Characteristics
 Software: Bioinformatics tools and software (e.g., BLAST, MEGA, RAxML) are
used to analyze large datasets of genetic information, including sequences, gene
 Leaves: Shape, size, arrangement, venation, and
expressions, and SNPs.
 Applications: These tools help in aligning DNA sequences, constructing phylogenetic type (simple or compound).
trees, and identifying genetic markers associated with specific traits or diseases.  Stems: Type (herbaceous or woody), branching
pattern, and texture.
2. Databases:  Flowers: Structure (number of petals, sepals),
arrangement (inflorescence type), and reproductive
 Repositories: Large databases such as GenBank, the Plant Ontology Database, and parts (stamens, pistils).
the Phytozome provide access to extensive genetic and genomic data.
 Fruits and Seeds: Type of fruit (berry, capsule,
 Integration: Bioinformatics integrates data from various sources to provide a
comprehensive view of plant genetics, evolution, and taxonomy. drupe), seed structure, and dispersal methods.

3. Systems Biology: Learning to recognizes plants

 Holistic Approach: Bioinformatics supports systems biology by integrating genomic,

transcriptomic, proteomic, and metabolomic data to understand plant biology at a
systems level.
 Predictive Models: Computational models and simulations predict how plants will
respond to environmental changes or genetic modifications.

4. Data Visualization:
Weeds Grass Crops
 Graphical Tools: Visualization tools help in interpreting complex data by creating
graphical representations such as phylogenetic trees, heat maps, and network 2. Anatomical Features
diagrams.
 Leaf Venation: Patterns such as parallel, pinnate, or reticulate.
Integration of Methods
 Cell Structure: Characteristics of tissues like xylem, phloem, and epidermal cells.
Combining molecular phylogenetics, morphological studies, and bioinformatics provides a  Wood Anatomy: Features such as vessel elements, tracheids, and growth rings.
more comprehensive understanding of plant relationships and taxonomy. For example:
3. Reproductive Structures
 Integrative Taxonomy: Using both genetic and morphological data to classify plants
ensures a more robust and accurate taxonomy.  Flowers and Inflorescences: Types (complete, incomplete, perfect, imperfect),
 Evolutionary Studies: Molecular data can confirm or refute hypotheses based on arrangement (raceme, panicle).
morphological traits, leading to refined classifications and evolutionary insights.
 Pollination Mechanisms: Characteristics of flowers related to their pollinators (bee,
Understanding plant groups helps in appreciating the diversity of the plant kingdom and the bird, wind).
roles plants play in ecosystems and human life.
4. Genetic and Molecular Characteristics
Study of Identification Characters  DNA Sequencing: Identifying genetic markers specific to species or groups.
 Molecular Phylogenetics: Understanding evolutionary relationships using genetic
The study of identification characters of plant groups is a fascinating and crucial aspect of
data.
botany and plant taxonomy. This field involves examining various traits and features that
5. Ecological and Environmental Factors

31 32
  Habitat: Type of environment where the plant grows (wetlands, drylands). It is distributed worldwide in about 400 genera and 12000 species. This family was formerly
 Adaptations: Traits that help plants survive in specific conditions (e.g., succulence in
known as the subfamily Papilionoideae, a subfamily of the legume family.
cacti).
Systematic Position
6. Economic and Practical Uses

 Medicinal Properties: Identification of plants used in traditional and modern Class- Dicotyledonae
medicine. Subclass- Polypetalae
 Agricultural Importance: Traits that affect crop yield, disease resistance, etc. Series- Calyciflorae
Order- Rosales
7. Field Techniques Family- Fabaceae
 Herbarium Specimens: Collection, pressing, and cataloging of plant samples for
Vegetative CharactersClitoria ternatea
reference.
 Field Guides and Keys: Using dichotomous keys and field guides to identify plants
 Habit – Plants are mainly herbs, but shrubs, trees, and vines are also widespread.
in their natural habitat.
 Root – Taproot with mostly nodular side branches (nodules contain the nitrogen-fixing
8. Taxonomic Classification bacterium Rhizobium).
 Stem – Climb a herb or wood, upright or tendril. Leaves: Alternating, rarely simple, generally
 Hierarchical System: Classification of plants into Kingdom, Phylum, Class, Order, complex pinnate, stationary, leaf-based pinnate, reticulated veins, leaves, or leaflets are
Family, Genus, and Species.
converted to tendrils.
 Synonyms and Nomenclature: Understanding the various names that a plant might
have due to historical and regional variations.
Floral Characters
9. Recent Advances
 Inflorescence – solitary or Racemose
 Remote Sensing: Using satellite imagery and drones for large-scale plant monitoring  Flower – Stalker, bract, bisexual, junctional morphology, perigin, sometimes pituitary, 5x.
and identification.  Calyx – Sepals five, gamosepalous, valvate/imbricate aestivation.
 AI and Machine Learning: Implementing algorithms to identify plants from images  Corolla – It consists of five petals, multi-petals, papillionate, posterior wing, two lateral
and other data. wings, two anterior wings forming a keel (surrounding the stamen and pistil), and
The study of plant identification characters involves a multi-faceted approach, integrating beautification of the pistil.
morphological, anatomical, reproductive, genetic, and ecological information. Techniques  Androecium – 10 Diadelphos (9 congenital and 1 free), anther dithek.
and tools continue to evolve, enhancing our ability to understand and classify the vast  Gynoecium – Excellent single ovules of the ovary, one chamber with many ovules, isolated
diversity of plant life. style, many ovules in two alternating rows.
 Fruit – Legumes or pods. Seeds: One-to-many, no endosperm.
Study of important families of Angiosperms
Angiosperms are vascular plants with stems, roots, and leaves. The seeds of the angiosperm Economic Importance
are found in a flower. These make up the majority of all plants on earth. The seeds develop
inside the plant organs and form fruit. Hence, they are also known as flowering plants.  Pulses: This family is the source of some pulse crops such as Gram(chana), arhar (Pigeon
Angiosperms are the most advanced and beneficial group of plants. They can grow in various pea), moong (Green gram), soybean, etc.
habitats as trees, herbs, shrubs, and bushes.  Fodder: Trifolium, Sesbania, etc.
 Edible oil: Groundnut and soybean are used as cooking oil, preparation of soaps, cosmetics,
1. Fabaceaes etc.

33 34
 Dyes: Indigo dye obtained from Indigofera.  Androcea: five stamens. Anther, anther bitheca.
 Fibres: Plants belonging to this family are also used  Gynecology: flagellate, diploid, upper ovary with an oblique septum, bicellular, placental
as fodder, e.g., Sunhemp abruption with many eggs, placenta attached to the armpit.
 Ornamental: Common ornamentals are lupin  Fruit: berry or capsule containing many seeds
(Lupinus), sweet pea (Lathyrusodoratus)
 Medicines: The roots of Multipath Economic Importance
(Glycyrrhizaglabra) are used in relieving
 Food: This family includes numerous plants that produce vegetables and other edible
inflammation and treating gastric ulcers; seeds of Buteamonosperma Cassia auriculata
products. B. Solanumtuberosum (potato), Lycopersiconesculentum (tomato),
 have antifungal and anthelmintic properties.
Solanummelongena (eggplant), Capsicum annuum (chili pepper), etc.
2. Solanaceae
 Tobacco: Derived from the dried and weathered leaves of Nicotianatabacum. It is a
It is a large family, represented by about 90 genera and 2,800 species commonly known as fumigation plant.
the potato family. It is generally distributed in tropical, subtropical, and temperate regions.  Medicines: Plants such as Atropa belladonna, Hyoscyamusniger, and Datura offer many
valuable medicines.
Systematic Position  Ornamental plants: Common ornamental plants are petunia, jessamine, etc.

Class- Dicotyledonae

Subclass- Gamopetalae

Series- Bicarpellatae

Order- Polyminales

Family- Solanaceae 3. Liliaceae

Vegetative Characters It is commonly referred to as the Liliaceae family and includes 250 genera and 3700 species.
The plants that belong to this family are monocotyledonous. They are widespread all over the
 Habit: Mainly herbs, sometimes shrubs and trees. Rarely vines.
world.
 Route: Naone.
 Stems: Herbaceous, rarely woody, airy, upright, cylindrical, stiff, branched or hollow, hairy Systematic Position
or hairless (smooth), potato (Solanumtuberosum) rhizomes.
 Leaves: Alternating, simple, rarely pinnate, molting, hairy, net-like stripes. Class- Monocotyledonae

Floral Characters Series- Coronarieae

 Inflorescence: Solitary, in leaf axils or cymbal as in Solanum. Family- Liliaceae

 Flowers: Bracts or bracts, pedunculate, hermaphroditic, active, pentagonal, borne.
 Calyx: Calyx five, fused, persistent, valuable, gamosepalous. Vegetative Characters
 Corolla: Five Petals, Gamopetales, Valuation.

35 36
 Growth: A perennial herb with main rhizomes, tubers, and rhizomes.
 Roots: Random, fibrous.
The Rosaceae family, or the rose family, is indeed
 Stems: aerial or underground, herbaceous or woody. Leaf: Mainly with basal, alternating,
a fascinating and economically significant group
linear, and parallel veins. of plants. Here’s a bit more detail on its
characteristics and importance:
Floral Characters
Characteristics
 Inflorescence: Solitary/cymose, often in umbel-like clusters.
 Flowers: Bisexual, active.  Diverse Fruits: This family includes a wide
 Perianth: Six tepals (3 + 3). Usually linked into a tube control valve. range of fruit types such as pomes (apples, pears),
drupes (cherries, peaches), and aggregate fruits
 Androcea: Stamens six, (3 + 3).
(strawberries, raspberries).
 Gynoecium: Triangle, upper ovary, three carpels with multiple ovules, ovate placenta.
 Leaves: Members often have compound leaves,
 Fruit: Rarely berry, Capsule. which means the leaf blade is divided into several
 Seed: Endosperm leaflets. They also frequently possess stipules—
small leaf-like structures at the base of the leaf
Economic Importance stalk.
 Flowers: Flowers in this family are typically five-
 Food: Boil the young shoots and roots of asparagus. The bulbs of Allium cepa and Allium petaled and have numerous stamens, which
sativum are used as vegetables. contributes to their ornamental appeal.
 Medicines: Aloe is a source of medicines. Medicinal oil is prepared from the asparagus root.
Economic Importance
 Ornaments: Gloriosa and tulips are common ornamental plants.
 Colchicine: Colchicumautumnale produces colchicine, which is used for chromosome  Fruits: The family is crucial for agriculture due to its production of many popular
replication. fruits. Apples (Malus) and strawberries (Fragaria) are staples in many diets
worldwide.
 Ornamental Plants: Roses (Rosa) are highly valued for their beauty and are a major
part of floral arrangements and landscaping.
 Medicinal Plants: Some members have medicinal uses. For example, rose hips (the
fruit of the rose) are used in herbal remedies and teas for their high vitamin C content.

Examples

 Roses (Rosa): Known for their aesthetic appeal and use in perfumes and decorations.

5. Orchidaceae (Orchid Family)

 Characteristics:
o Complex Flowers: Orchid flowers are known for their intricate and highly
specialized structures, often featuring bilateral symmetry and a unique
arrangement of floral parts.
 o Habitats: Many orchids are epiphytic, growing on other plants for support,
but there are also terrestrial species.
 Economic Importance:

37 38
 o Cut Flowers: Orchids are a major player in the cut flower industry, prized for o Lettuce (Lactuca sativa): A staple leafy vegetable in salads.
their exotic appearance and long-lasting blooms.
o Horticulture: They are popular among collectors and gardeners for their 7. Brassicaceae (Mustard Family)
diverse and striking floral forms.
 Examples:  Characteristics:
o Phalaenopsis (Phalaenopsis): Often called "moth orchids," known for their o Four-Petaled Flowers: Members typically
broad, flat flowers. have flowers with four petals arranged in a
o Cattleya (Cattleya): Famous for their large, fragrant flowers used in corsages. cross shape.
o Vanilla (Vanilla planifolia): The source of vanilla flavoring; its beans are o Fruit Types: Produce siliques or silicles,
used in culinary applications. types of seed pods.
o Flavor: Many species are known for their
pungent or spicy flavors.
 Economic Importance:
o Vegetables: Includes important food crops such as broccoli and cabbage.
o Oil Crops: Mustard seeds are used to produce mustard oil.
 Examples:
o Mustard (Brassica): Used both as a spice and in oil production.
o Broccoli (Brassica oleracea): A popular vegetable rich in nutrients.
o Radishes (Raphanussativus): Known for their crisp texture and peppery
flavor.

8. Apiaceae (Carrot Family)

 Characteristics:
o Compound Umbels: Flowers are
6. Asteraceae (Daisy Family) arranged in clusters known as umbels,
with smaller clusters branching off from
 Characteristics: a common point.
o Composite Flowers: This family is characterized o Aromatic Leaves: Many species have
by composite inflorescences, where multiple small aromatic foliage.
flowers (florets) are clustered together to form a o Fruit Type: Fruits are typically
single "head." schizocarps, which split into two single-
o Forms: Includes a wide variety of plant forms, seeded parts when mature.
from small herbs to large shrubs.  Economic Importance:
 Economic Importance: o Culinary Herbs: Includes widely used
o Crops: Includes important agricultural crops like herbs and vegetables.
lettuce and sunflowers. o Medicinal Plants: Some species are
o Medicinal Plants: Some species have traditional medicinal uses. used in traditional medicine.
o Ornamentals: Many species, such as daisies, are popular in gardens and floral  Examples:
arrangements. o Carrots (Daucuscarota): A widely
 Examples: consumed root vegetable.
o Sunflowers (Helianthus): Valued for their seeds and oil, as well as their o Celery (Apiumgraveolens): Known for
large, attractive flowers. its crisp stalks used in salads and
o Daisies (Bellis): Commonly grown for their simple and cheerful appearance. cooking.

39 40
 o Coriander (Coriandrumsativum): Both the leaves (cilantro) and seeds  Apples (Malus): One of the most widely consumed fruits globally, used in various
(coriander) are used in cooking. culinary applications.
 Strawberries (Fragaria): Popular for their sweet flavor, often eaten fresh or used in
9. Myrtaceae (Myrtle Family) desserts and jams.
 Raspberries (Rubus): Valued for their taste and nutritional benefits, used in both
 Characteristics: fresh and processed forms.
o Aromatic Oils: Many members produce
aromatic oils in their leaves. The Rosaceae family’s variety and utility make it a key player in horticulture and agriculture.
o Fruit Types: Can produce a variety of fruit
types including berries and capsules.
o Flowers: Often have showy flowers with
numerous stamens. There are many flowering plants on our planet, which are divided into different families and
 Economic Importance: subfamilies based on specific morphological characteristics. There are certain important
o Fruit Crops: Some species are grown for families, such as legumes and legumes, which have diadelhus anthers in addition to grape
their edible fruits. anesthesia and nodules for nitrogen fixation. The Solanaceae or Potato family shows the
o Ornamentals: Includes decorative plants used in gardens and landscaping. association between corolla and stamens (petals) and calyxes. Solanaceae show bisexual
 Examples: flowers with the beautification of bar butter. Liliaceae or Liliaceae have bulbous roots with
o Guava (Psidiumguajava): Produces sweet, edible fruits rich in vitamin C. parallel leaves, the flowers of which are perianths and pituitary.
o Feijoa (Feijoasellowiana): Known for its aromatic fruit.
o Myrtles (Myrtus): Ornamental shrubs with aromatic leaves and colorful Characteristics of Angiosperms
flowers.
Angiosperms have diverse characteristics. The important characteristics of angiosperms are
10. Rutaceae (Rue Family) mentioned below:

1. All plants have flowers at some stage in their life. The flowers are the reproductive
 Characteristics:
organs for the plant, providing them with a means of exchanging genetic information.
o Aromatic: Plants often have aromatic leaves
due to glandular punctate structures. 2. The sporophyte is differentiated into stems, roots, and leaves.
o Citrus Fruits: Many species produce citrus
3. The vascular system has true vessels in the xylem and companion cells in the phloem.
fruits with a high vitamin C content.
 Economic Importance: 4. The stamens (microsporophyll) and the carpels (megasporophyll) are organized into a
o Citrus Fruits: Major sources of fruit such as structure called the flower.
oranges and lemons.
5. Each microsporophyll has four microsporangia.
o Essential Oils: Used in perfumes and
flavorings. 6. The ovules are enclosed in the ovary at the base of the megasporophyll.
 Examples:
7. Angiosperms are heterosporous, i.e., produce two kinds of spores, microspore (pollen
o Oranges (Citrus sinensis): Widely consumed fresh and as juice.
grains) and megaspores.
o Lemons (Citrus limon): Used for their tart flavor in cooking and beverages.
o Rue (Ruta): Known for its medicinal properties and aromatic leaves. 8. A single functional megaspore is permanently retained within the nucellus.

Each of these plant families contributes significantly to agriculture, horticulture, and various 9. The pollen grains transfer from the anther to stigma and reproduction takes place by
industries through their unique characteristics and uses. pollination. They are responsible for the transfer of genetic information from one
flower to the other. The pollen grains are much smaller than the gametophytes or
 reproductive cells present in the non-flowering plants.
10. The sporophytes are diploid.

41 42
 11. The root system is very complex and consists of cortex, xylem, phloem, and Plant Diversity Application
epidermis.
Plant diversity has numerous applications across various fields, each leveraging the rich
12. The flowers undergo double and triple fusion which leads to the formation of a
variety of plant species to address specific needs or solve particular problems. Here’s a
diploid zygote and triploid endosperm. breakdown of how plant diversity is applied in different areas:
13. Angiosperms can survive in a variety of habitats, including marine habitats.
1. Agriculture and Food Security
14. The process of fertilization is quicker in angiosperms. The seeds are also produced
quickly due to the smaller female reproductive parts.  Crop Improvement: Diverse plant species provide a genetic pool for breeding
15. All angiosperms are comprised of stamens which are the reproductive structures of programs to develop crops with desirable traits such as disease resistance, drought
the flowers. They produce the pollen grains that carry the hereditary information. tolerance, and enhanced nutritional content.
 Sustainable Farming: Plant diversity in crop rotations and intercropping systems
16. The carpels enclose developing seeds that may turn into a fruit. helps manage pests and diseases, reduces soil erosion, and improves soil fertility
17. The production of the endosperm is one of the greatest advantages of angiosperms. through nitrogen-fixing plants.
The endosperm is formed after fertilization and is a source of food for the developing  Food Security: Diversity ensures a variety of food sources, which can be crucial for
seed and seedling. resilience against crop failures and climate change.

Classification of Angiosperms 2. Medicine and Health

The classification of angiosperms is explained below:  Pharmaceuticals: Many modern medicines are derived from plant compounds.
Diverse plant species offer a vast reservoir of potential new drugs and therapeutic
Monocotyledons agents.
 The seeds have a single cotyledon.  Traditional Medicine: Plant diversity is fundamental to traditional medicine systems
around the world, providing treatments for various ailments based on local plant
 The leaves are simples and the veins are parallel. knowledge.
 This group contains adventitious roots.  Nutritional Supplements: Plants provide essential vitamins, minerals, and
antioxidants that support human health.
 Each floral whorl has three members.
 It has closed vascular bundles and large in number. 3. Horticulture and Landscaping

 For eg., banana, sugarcane, lilies, etc.  Ornamental Plants: Plant diversity contributes to aesthetic appeal and design in
gardens, parks, and urban landscapes, offering a range of colors, shapes, and textures.
Dicotyledons  Environmental Landscaping: Native and adapted plant species are used in
landscaping to restore natural habitats, improve biodiversity, and reduce maintenance
 The seeds of these plants have two cotyledons.
costs.
 They contain tap roots, instead of adventitious roots.
4. Ecological Conservation
 The leaves depict a reticulate venation.
 The flowers are tetramerous or pentamerous and the vascular bundles are organized in  Habitat Restoration: Plant diversity is crucial for restoring degraded ecosystems,
rings. rebuilding natural habitats, and promoting ecological resilience.
 Biodiversity Conservation: Protecting plant diversity helps maintain ecosystem
 For eg., grapes, sunflower, tomatoes, etc.
functions, supports wildlife, and preserves genetic resources.
The angiosperms originated about 250 million years ago and comprise 80% of earth’s plant
life. They are also a major source of food for humans and animals. 5. Climate Change Mitigation

43 44
  Carbon Sequestration: Diverse plant species, especially forests, play a significant UNIT II
role in capturing and storing carbon dioxide, thus mitigating the effects of climate
change. INTRODUCTION TO ANIMAL DIVERSITY AND TAXONOMY
 Adaptation Strategies: Plant diversity can help ecosystems adapt to changing climate
conditions by providing species that are resilient to new environmental stresses. Animal diversity refers to the variety of animal species and their differences within
ecosystems and across the globe. It encompasses a wide range of characteristics, including
6. Economic Development form, function, behaviour, and habitat. Animals show variations in their anatomy,
physiology, and genetic features. Based on those differences, they are put into different
 Agricultural Products: Plant diversity supports various industries, including food categories.The study of zoology includes the interaction of animal kingdom in their
production, beverages, textiles, and biofuels, contributing to economic growth. ecosystems such as classification, habits, structure, embryology, distribution, evolution, and
 Tourism: Botanical gardens, natural parks, and diverse plant landscapes attract extinct species.
tourists and support local economies.
Several factors contribute to animal diversity, including habitat diversity, competition
7. Cultural and Social Values among species, and genetic diversity. It is estimated that around 9 or 10 million species of
animals inhabit the earth. Animals range in size from no more than a few cells to organisms
 Cultural Heritage: Plants have deep cultural significance in many societies, weighing many tons, such as blue whales and giant squid. Animal diversity provides a boost
including roles in rituals, ceremonies, and traditional practices. to the ecosystem's productivity, where each species, no matter how small, has a vital role to
 Education and Research: Plant diversity provides a rich field for scientific research, play. Diversity is thus a critical indicator of the health of an ecosystem.
educational programs, and public awareness about the importance of plants in our
Animal taxonomy is a science that deals with identifying, classifying and naming of animals.
lives.
Animals are classified based on the Linnaeus classification system. Taxonomists place them
8. Biotechnology and Genetic Resources in the hierarchical order starting with kingdom and proceeds through phyla, classes, orders,
family, genera, and species.
 Bioprospecting: Researchers explore plant diversity to discover new biological
Taxonomists divided the animal kingdom into two main categories which include vertebrates
compounds and enzymes for industrial applications, including bioremediation and
and invertebrates. Invertebrates phylum includes arthropods, molluscs, and annelids.
bioengineering.
Vertebrates include mammals, birds, reptiles, fish, and amphibians.
 Genetic Engineering: Plant diversity offers genetic material for developing
genetically modified organisms (GMOs) with improved traits for agriculture and
industry.

9. Soil Health and Erosion Control

 Soil Stabilization: Plant diversity, particularly through ground cover and root
systems, helps prevent soil erosion and maintains soil structure.
 Nutrient Cycling: Different plant species contribute to nutrient cycling and soil
fertility through various root structures and decomposition processes.

By applying plant diversity in these areas, we harness the ecological, economic, and social
benefits that contribute to sustainability and resilience in both natural and human-managed
environments.

45 46
Principles and Rules of Taxonomy discoveries, especially molecular data, can lead to revisions in taxonomic
classifications.
Principles of Animal Taxonomy portrays the scientific quest regarding nomenclature,
identification, interrelationship of different groups of animals along with different aspects of These principles help scientists communicate clearly about animal species, understand their
taxonomy from Linnaeus to present day Aspects related with biodiversity, information relationships, and organize the vast diversity of life in a meaningful way.
retrieval, collection and preservation of animals
Rules of Taxonomy
Hierarchical Classification
Taxon (pl. taxa): a named group of organisms.
Definition: Organisms are classified into a hierarchical structure of ranks, each representing a
different level of organization. This hierarchy typically includes Domain, Kingdom, Phylum, Traditionally, each culture had its own name for the animals, plants, and other organisms in
Class, Order, Family, Genus, and Species. their region. But EACH culture had its own set of names, so the same type of animal might
Purpose: This system provides a structured way to organize and categorize the vast diversity have many different names. During the 1600s and 1700s, methods were proposed for a
of animal life, reflecting their evolutionary relationships. formal scientific set of names.

Binomial Nomenclature Carlos Linnaeus developed a universal set of rules in the SystemaNaturae ("System of
Nature") in 1758; later workers added and modified the system (primarily with the addition
Definition: Each animal species is given a two-part scientific name consisting of the genus of new "ranks").
name and the species epithet (e.g., Pantheraleo for lions).

Purpose: This system ensures that each species has a unique and universally recognized Some of the Linnaean rules:
name, avoiding confusion from common names and facilitating clear scientific
 All names are in Latin or Greek, or are modified into Latin form;
communication.
 Each name must be unique;
 All names are fit into a nested hierarchy (species into genera, genera into families, and
Animal taxonomy is the science of classifying and naming animals. It’s based on several core
principles: so forth);
 In traditional Linnaean taxonomy, there is a set of official ranks (from smallest to

Phylogenetics: Taxonomy often reflects evolutionary relationships. Phylogenetics largest, species, genus, family, order, class, phylum) (later workers added additional
uses genetic, morphological, and sometimes behavioral data to infer these intermediate ranks, such as tribes, subfamilies, superfamilies, subphyla, etc.);
relationships and classify organisms based on their evolutionary history.  The primary unit is the species (pl. species):
Monophyly: Groups should ideally be monophyletic, meaning they include a
 Refers to a "specific" kind of organism
common ancestor and all its descendants. Monophyletic groups are preferred because
 Definition of a "species" varies from biologist to biologist; some
they reflect natural evolutionary relationships.
definitions ("naturally occurring interbreeding populations") cannot be
Taxonomic Ranks: The various ranks (e.g., Family, Genus) help organize species
tested for fossils!
into a structured system. These ranks can sometimes be adjusted as more information
 More about species below
about evolutionary relationships becomes available.
 Each species has a type specimen accessioned in an appropriate
Type Specimens: A type specimen is a reference specimen used to describe a species.
institution (museum, zoological or botanical garden, or other such
The species name is fixed to this specimen, and it serves as the basis for comparison
collection);
with other specimens.
 Whoever describes the type specimen of a new species has the right to
Stability and Consistency: Taxonomy aims to be stable and consistent. This means
name that new species (following the rules below);
following rules and guidelines (like those set by the International Code of Zoological
Nomenclature) to avoid confusion and ensure that names and classifications are
 The next higher unit, the genus (pl. genera) is composed of one or more species
standardized across the scientific community.
Evolutionary Change: Taxonomy is not static. As new information about  Refers to a more "generic" category than species
evolutionary relationships becomes available, classifications can change. New

47 48
  Definition of a "genus" is problematic as well, since it is composed of 4. Name Changes: If a name is found to be preoccupied or invalid for other reasons, it may
one or more "species"; be replaced with a new name. The replacement name should adhere to the Code's guidelines
 Each genus has a type species: all other species are assigned to the
to avoid further confusion.
genus based on their similarity to the type species;

5. Publication: For a name to be valid, it must be published in a manner that is accessible to

Linnaean taxonomy has its own special set of grammatical rules:
the scientific community. This includes meeting requirements for formal description and
 Genera have one word names (e.g., Panthera, Homo, Ginkgo, Tyrannosaurus); publication.
o The genus name is always Capitalized and italicized (or underlined if you
don't have access to italics); 6. Taxonomic Ranks: The ICZN specifies how names at different taxonomic ranks (species,
 Species have two word names, the first part of which is the same as the genus name
(e.g., Pantheraleo, Homo sapiens, Ginkgo biloba, Tyrannosaurus rex) genus, family, etc.) should be used and how they should be formatted.
o The genus name is ALWAYS capitalized, the second part ("trivial nomen")
7. Correction of Errors: The Code provides guidelines on how to correct errors in names,
is ALWAYS in lower case, and the name is ALWAYS italicized or
underlined; such as typographical errors or incorrect author citations.
o Species names can be abbreviated by using only the first letter of the genus
name, followed by a period (NEVER by a hyphen): H. sapiens and T. rex are 8. Rejection of Names: Under certain circumstances, names can be rejected if they violate the
correct; H. Sapiens or T-Rex are WRONG!! (Subtle hint: do not use the Code’s rules or if they are deemed confusing or misleading.
incorrect form on your homework or tests).
Principle of ICZN rule
ICZN Rules
The following are six main principles of ICZN:
The full form of ICZN is the International Code of Zoological Nomenclature.
This ensures the scientific name assigned to the animal has one name and is
Principle of Binomial nomenclature
recognized all over the world by the scientific community.
These codes make sure that each organism gets a specific name and that name is
According to this principle, the scientific name of a species is a combination of
globally identified.
The naming follows certain conventions. two names. The name of the species is composed of Generic name and Specific
Each scientific name has two parts: A generic name and a Specific epithet.
name.
Rules of ICZN rule
Principle of Priority
1. Nomenclatural Availability: For a name to be available for use, it must be properly
According to this principle, the correct formal scientific name is the oldest
published according to the Code’s requirements (e.g., in a recognized scientific journal or
book). available valid name

2. Proper Citation: Names must be properly cited, including author and year of publication, Principle of coordination

to ensure their validity and avoid confusion. According to this principle, when a new zoological name is published, it

3. Correct Spelling: The name must be spelled according to the rules of the Code. automatically establishes all corresponding names in relevant ranks.
Misspellings or incorrect forms might render a name unavailable.
Principle of First Reviser

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This principle is applied in case of conflicts between published names. When a Key Components of Animal Study:
conflict arises between two simultaneously published divergent names, the first 1. Observation: Watching animals in their natural habitat or in controlled settings to
record behaviors, interactions, and other phenomena.
subsequent author can decide which name has precedence.
2. Experimentation: Conducting controlled experiments to test hypotheses about
animal behavior, physiology, or ecology. This may involve manipulating variables
Principle of Homonymy
and observing the effects.
According to this principle, the name of each taxon must be unique and must not 3. Sampling and Measurement: Collecting biological samples (e.g., blood, feces,
feathers) and measuring physiological and environmental parameters to analyze
be replicate or duplicate of any other family, group or species. various aspects of animal health, genetics, and ecology.
4. Data Analysis: Using statistical and analytical methods to interpret data collected
Principle of Typification from observations, experiments, and samples.
5. Ethical Considerations: Ensuring that studies are conducted with respect for animal
According to this principle, each nominal taxon in the family group, genus group welfare, minimizing harm and distress, and adhering to legal and ethical guidelines.

or species group must have a prefixed name- bearing type. This helps in Animal studies aim to increase our understanding of the natural world, inform conservation
efforts, improve animal welfare, and provide insights that can be applied to related fields such
determining what name it applies to.
as medicine, environmental science, and behavioural science.

Types of Studies in animal study

Animal Study Techniques  In vivo

 Invitro
 Exvivo
Animal study refers to the systematic and scientific investigation of animals to understand  Bioassys
various aspects of their biology, behavior, ecology, and interactions with their environment. It
encompasses a range of methods and approaches used to gather data and insights about
animals, aiming to advance knowledge in fields such as zoology, ethology, ecology, and
conservation biology.

Studying animals involves a variety of techniques that help researchers understand their
diversity, behavior, physiology, and evolutionary relationships. Here’s an overview of the
key techniques used in animal studies:

51 52
1. Observation Techniques understand cognitive functions and behavioral strategies.

 Field Observations: Observing animals in their natural 5. Physiological Measurements

habitat to understand their behavior, social interactions, and
ecological roles. This can include watching animals interact  Blood and Tissue Sampling: Collecting biological
with their environment, other species, and their own kind. samples to analyze hormones, genetics, or health
 Laboratory Observations: Conducting observations in a indicators. This is crucial for studying disease,
controlled environment to study specific aspects of animal reproductive status, or stress levels.
behavior, physiology, or responses to experimental  Telemetry Devices: Using sensors to monitor
conditions. physiological parameters such as heart rate, body
temperature, or activity levels in real-time, often used
2. Tracking and Monitoring in studies of stress or health.

 Radio Telemetry: Attaching radio transmitters to animals 6. Genetic Analysis

to monitor their movements and behaviorsover time. This
technique is useful for studying animals that travel large distances  DNA Sequencing: Analyzing genetic material to study
or have elusive habits. genetic diversity, population structure, and evolutionary
 GPS Tracking: Using GPS devices to track animals' relationships among species.
 Gene Expression Studies: Investigating how gene activity
precise locations and movement patterns, often employed in
changes in response to environmental factors, developmental
studies of migration and habitat use.
stages, or experimental conditions.
 Camera Traps: Deploying motion-activated cameras in
the field to capture images or videos of animals without human
7. Ecological Surveys
presence. This technique helps in studying elusive or nocturnal
species.  Population Surveys: Estimating animal populations through direct counts, sightings,
or indirect evidence like tracks and feces. These surveys help in assessing population
3. Tagging and Marking trends and distribution.
 Habitat Assessments: Evaluating habitat characteristics and quality to understand
 Physical Tags: Attaching visible tags (e.g., ear tags,
their impact on animal populations and behaviors.
leg bands) to animals for individual identification and
monitoring. These are often used in studies of
8. Ethological Methods
population dynamics and movement patterns.
 Microchipping: Implanting small microchips that can  Focal Animal Sampling: Observing a single individual for a set period to record
be scanned to identify and track animals. This method detailed behavioral data, often used to study social interactions or specific behaviors.
is often used for pets and in some research settings for  Scan Sampling: Recording the behavior of all individuals in a group at specific
wildlife. intervals to get a snapshot of the group's overall activity.

9. Experimental Manipulations
4. Behavioral Experiments
 Enrichment Experiments: Introducing changes to the environment to provide
 Controlled Experiments: Manipulating environmental stimulation and assess their effects on animal behavior and well-being. This technique
variables in a lab setting to observe animal responses, such as is commonly used in captivity to improve animal welfare.
learning, memory, or problem-solving capabilities.  Deprivation Experiments: Studying the effects of removing or altering certain
 Choice Tests: Providing animals with options to study their aspects of the environment or diet to understand their impact on animal health and
preferences and decision-making processes, often used to behavior.

53 54
10. Audio Recordings:  The taxonomic categories biology is necessary because it helps us in the process of
classification.
Recording animal vocalizations to study communication and
behaviour.  Further, we will learn more about taxa meaning, taxonomic categories, and the
different categories in which classification has been done.
11. Morphological Techniques
Taxonomic Categories
Anatomical Dissection:
 It is not a single step process of classifying living organisms. It takes place in
Examining internal structures through dissection to understand multiple steps.
organ systems and developmental stages.
 A rank of the category is represented at each step in the hierarchy of steps. As
these categories are a part of the taxonomic arrangement, it is known as the
Microscopy:
taxonomic category.
Using microscopes to view small structures and tissues not  When all these taxonomic categories come together, it forms a taxonomic
visible to the naked eye. hierarchy.

Morphometric Analysis: Taxa in Biology

 Taxa are the plural word for the taxon. The taxon represents a level of grouping
Measuring and analyzing the shape and size of organisms to
of organisms that is based on some easily observable characteristics.
study variation and evolutionary relationships.
 This is the difference between taxa and taxon. For example, like in insects,
Animal study techniques encompass a wide range of methods, each tailored to different they can be classified on the basis of some features like three pairs of jointed
research objectives. From observational studies in the wild to controlled laboratory legs.
experiments, these techniques provide valuable insights into animal behavior, physiology,
and evolutionary relationships. By applying these methods, researchers can deepen our  By this feature, the insects can be uniquely recognized and classified. Due to
understanding of animal diversity and taxonomy, ultimately contributing to conservation
this, they were given a definite rank or category in the taxonomic hierarchy.
Similarly, the birds can represent that group of organisms that have feathers,
efforts, animal welfare, and our knowledge of biological processes.
hollow bones and beaks. As they have different features from that of insects, so
they are kept in different taxonomic hierarchies.
Concepts of Taxon
 By remembering their ranks and taxon's we can memorise them. The rank or
Taxon Definition the taxon represents the group of organisms that share some different features
 This definition will answer our question of what is taxon. Taxonomy is made from that are unique among the members of their group.
two Greek words: ‘taxis’ and ‘nomos'.
 These are obviously different from the organisms that are kept in another
 Aristotle is known as the father of taxonomy. A taxon meaning is that it is a group of taxon. So in this way, these taxonomic groups form the groups or categories
one or more than one populations of organisms. that are distinct biological entities and they must be thought of as random
aggregates of animals that are based on morphological features. This is the
 These are seen by the taxonomists to form a unit. The taxonomy or taxa biology is the actual taxa meaning.
branch of science that deals with the study of principles and the procedures that are
required for classification. Taxonomical Aids

 The word taxa signifies the taxonomic group of any rank. The taxa are known by a . These taxonomical aids can help us in:
particular name and they are also given a particular ranking.  Making a fundamental study of different living organisms
 It also helps us in providing aid in their systematic study.

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  The gathered information is stored for future studies. o The families of cats and the families of dogs are kept under the same
order as Carnivora. They both have canine teeth.
Keeping this in mind, the biologists have made certain procedures and techniques for storing
and preserving the information. Some of these resources that provide us with the information  Family:
are herbarium, Botanical gardens, Museums and Zoological parks.
o This category is lower than that of order.
Categories of Classification o It includes various groups that are related to each other by their genera.
They share fewer similarities as compared to that at the genus and
There are very diverse kinds of organisms that are known and are studied by species level.
scientists. These are also known as ranks of classification. There are seven categories
and we will understand them below.  Genus:
 Kingdom: o It is made up of a group of related species. The genus has more
characteristics in common as compared to the species of the other
o It is the first and the highest category in the taxonomic hierarchy. It is genera.
made up of a group of phyla that have certain basic common
characteristics.  Species:
o Animalia is one of a kingdom. The animals that are present in this phyla o It refers to the natural population of individuals or groups of species that
lack a cell wall and chlorophyll. resembles one another in some of the other morphological or
o The ones that are present in kingdom Plantae have rigid cell walls reproductive characters.
around their cells and they also synthesize their own food by the process Taxon Examples
of photosynthesis. In short, they are also known as animal and plant Now, let’s list some taxa examples at different levels of the taxonomic hierarchy.
kingdom.
Taxon examples at the level of “kingdom” Taxon examples at the level of
 Phylum:
“division/phylum”
o It is also known as division. This category is lower than that of the  Animalia (animals)
kingdom. Phylum term is used for animals and division is used for  Plantae (plants)  Bryophyta (bryophytes)
plants.  Protista (protists)  Pteridophyta (pteridophytes)
 Fungi  Gymnosperms
o It comprises different classes. Like fishes, amphibians, birds, reptiles  Angiosperms
and mammals, all of them make a phylum Chordata.
 Arthropoda (arthropods)
 Echinodermata (echinoderms)
 Class:
 Nematoda (nematodes)
o They are a diverse group of different phyla or a group of one or more
related orders. Examples of bacterial phyla: Actinobacteria,
Bacteroidetes, Cyanobacteria, etc
o Like the monkey, gorilla, gibbon, all make the same class of Mammalia.
They are kept under the same class because all of them have milk-
producing glands and hair on their body.
Taxon examples at the level of “class” Taxon examples at the level of “order”
 Order:
 Gastropoda Some taxon orders are:
o It is a diversion of class or a group of related families.  Cephalopoda
 Chondrichthyes  Sapindales
 Bryopsida  Pinales

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  Sphagnopsida  Ginkgoales Types of Taxa
 Primates
 Protura  Monophyletic Taxa: Groups that include a common ancestor and all of its
 Diplura descendants (e.g., the genus Homo).
 Collembola  Paraphyletic Taxa: Groups that include a common ancestor but not all of its
descendants (e.g., reptiles, excluding birds).
 Polyphyletic Taxa: Groups that do not share a common ancestor within the group
Taxon examples at the level of “family” Taxon examples at the level of “genus” (e.g., flying animals like birds and bats, which have evolved flight independently).

 Solanaceae  Aesculus Taxonomic Classification Systems

 Cactaceae  Melicoccus
 Apororhynchidae  Dimocarpus  Traditional Taxonomy: Based on morphological and anatomical features.
 Moniliformidae  Azorella  Phylogenetic Taxonomy: Based on evolutionary relationships and genetic data,
emphasizing common ancestry.
 Cladistics: A method of classification that uses shared derived characteristics to
Taxon examples at the level of “species” establish evolutionary relationships.

Taxonomic Revisions

 Taxonomic classifications are not static. They can change with new discoveries and
advances in technology (e.g., genetic sequencing). As a result, organisms may be
reclassified into different taxa as our understanding of their relationships evolves.

Role of Taxonomy

 Taxonomy is essential for organizing biological diversity, understanding evolutionary

relationships, and communicating scientific information. It provides a framework for
studying and conserving biodiversity.
 Understanding these concepts helps in grasping how scientists categorize and relate
the vast diversity of life on Earth.

Types of Specimens

1. Holotype: A single physical specimen designated as the type for a species when it is first
described. This specimen serves as the primary reference point for the species' identification
Fruit fly – taxonomic classification. and nomenclature. The holotype is typically preserved in a museum or research institution
and should be well-documented.
Binomial Nomenclature
 It is a single specimen.
This is a system for naming species, introduced by Carl Linnaeus. Each species is given a  It is used to describe particular species.
two-part Latin name:  The organism or fossil specimen is used to delineate the
characteristics of other members of that particular
 Genus Name: Capitalized. species.
 Thus, it is an original species' characteristics indicator
 Species Epithet: Lowercase. For example, Homo sapiensis the scientific name for
humans. Pelorosaurushumerocristatus

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 and needs to be preserved.  Definition:
 For example the holotype of Pelorosaurushumerocristatus is Duriatitan. Isotype: A specimen of a plant collected at the same time and place as the holotype, intended
to serve as an additional reference for the original type. It is part of the same collection event
2. Paratype: A specimen not formally designated as a type but cited along with the type and supports the original description of the species.
collection in the original description of a taxon.
 Example:
Definition:
One of these additional specimens, kept in a different herbarium but collected at the same
 Paratype: A specimen other than the holotype used to provide additional information time and place as the holotype, is referred to as an isotype. So, if Dr. Green's holotype is
about the variability and range of characteristics of a species or subspecies. housed in Herbarium A, another specimen from the same collection event that is housed in
 Example:Imagine a new species of butterfly is Herbarium B would be the isotype.
described, and the researcher designates a single
specimen as the holotype. This holotype is kept in a For example:
museum and serves as the reference for the species.
Along with the holotype, the researcher might also have  Holotype of Fernusuniqueus: Specimen #12345, Herbarium A.
several other butterflies collected from the same area  Isotype of Fernusuniqueus: Specimen #67890, Herbarium B, collected on July 10th
that show different color patterns or slight variations. from the same location in Costa Rica.
These additional specimens are called paratypes.
 Both specimens provide evidence for the species' characteristics and help ensure the accuracy
 of its identification and description.
3. Topotype: A specimen of a plant collected from the same locality as the holotype and
usually on a different date. A topotype has no formal standing.

A "topotype" refers to a specimen collected from the same location as the original type Orphanodendron and Camoensia. A).
specimens (holotype, paratype, etc.) of a species or subspecies. The term "topotype" is used Isotype of Orphanodendronbernalii,
to provide additional context and support for the original description of a species by showing Atrato River basin, Antioquia. B). Fruits
that other specimens from the same locality exhibit similar characteristics. of Orphanodendrongrandiflorum,
Magdalena River basin, Santander. C).
 Definition: Flowers of O. grandiflorum, Magdalena
River basin, Boyacá (photo: William
Topotype: A specimen collected from the
same locality as the type specimens (holotype Ariza). D). Camoensiascandens,
or paratypes) of a species or subspecies. cultivated in the Rio de Janeiro Botanic
Topotypes help to confirm and illustrate the Gardens.
characteristics of the species as described
from the original locality.

 Example: Suppose a new species of orchid, Orchidaceaerareus, is described based on a

single specimen collected from a specific rainforest in Brazil. The holotype is kept in a 5. Lectotype: Designated as the type when no holotype was identified by the original
herbarium. Later, a researcher discovers additional orchids in the same rainforest with the
author, or when the holotype is lost or destroyed. It is chosen from among the specimens
same distinctive features as the original specimen. These additional specimens, collected
from the same locality as the holotype, are referred to as topotypes. available to the original publishing author.

4. Isotype: An isotype is a specimen of a plant that is collected from the same location as  It is a specimen selected to serve as the single, definitive type specimen of a species
the original type specimen (holotype) of a species or subspecies and is part of the same or subspecies when the original description was based on multiple specimens or when
collection event. It is essentially a duplicate of the holotype, made at the same time and place, the original holotype is lost or was not clearly designated.
but kept in a different herbarium or collection.

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  The selection of a lectotype is necessary when a species description lacks a clearly Later, it is discovered that additional specimens from the same collection event were sent to
identified holotype or if the holotype is missing, and it helps to stabilize the Herbarium B. These additional specimens are duplicates of some of the original syntypes and
taxonomic reference for the species. are referred to as isosyntypes.

Definition:Lectotype: A specimen selected from the original collection to serve as the For instance:
single, definitive type specimen for a species or subspecies when no holotype was designated
or when the original holotype is missing or ambiguous.  Syntypes: Specimens #001, #002, #003 from Herbarium A, collected on July 15th.
 Isosyntypes: Specimens #004, #005, #006 from Herbarium B, collected on the same
6. Syntype: Any of two or more specimens listed in the original description of a taxon when date and from the same locality as the original syntypes.
a holotype was not designated.
In this context:
 It refers to any of the multiple specimens that were originally cited in a taxonomic
description when no holotype was designated.  Isosyntypes of Plantusexampleus: Specimens #004, #005, and #006 from Herbarium
 Syntypes are part of a series of specimens that collectively serve as the basis for the B, which are duplicates of the original syntypes.
description of a species or subspecies.
Isosyntypes are valuable because they provide additional material that can be used to confirm
 Unlike a holotype, which is a single, definitive specimen, syntypes are a group of
and support the original taxonomic description. They help ensure that the description of the
specimens that were considered together in the original description.
species is comprehensive and well-supported by multiple examples.
Definition:
8. Neotype: A specimen chosen by a later researcher to serve in place of a holotype when
Syntype: Any of the multiple specimens that were included in the original description of a all specimens available to the original publishing author of a scientific name have been lost or
species or subspecies when no single specimen was designated as the holotype. Syntypes destroyed.
collectively provide the basis for the species' description.
 It is a specimen designated to serve as the new type specimen for a species or
7. Isosyntype: A duplicate of a syntype. subspecies when the original type material (holotype, syntypes, etc.) is lost, destroyed,
or was never clearly designated.
 It is a type specimen that is part of the original series of specimens used to describe a  The neotype is selected to stabilize the taxonomy of the species and provide a clear
species or subspecies, and it is a duplicate or counterpart of the original syntypes. reference for its identification.
 These specimens are collected from the same locality and time as the original
syntypes but are housed in different collections or herbaria. Definition:

Neotype: A specimen chosen to serve as the new type for a species or subspecies when the
Definition:
original type material is missing, destroyed, or was never properly designated. The neotype is
Isosyntype: A specimen that is a duplicate of one of the original syntypes, collected from the selected to provide a clear, definitive reference for the species.
same locality and time as the syntypes, and stored in a different collection. Isosyntypes are
essentially additional specimens that are part of the original group used to describe a species. Example:

Dr. Smith described a new species of butterfly, Butterflyusextinctus, in 1900 based on several
Example: specimens. Over time, all of the original specimens (the holotype and any syntypes) are lost
or destroyed in a fire, leaving no physical reference for the species.
Dr. Green described a new species of flowering plant, Plantusexampleus, in 1920. Dr. Green
collected multiple specimens from a single locality in the Amazon rainforest and designated To resolve this issue and stabilize the taxonomy of Butterflyusextinctus, a taxonomist may
them as syntypes. These specimens are stored in Herbarium A. choose a new specimen collected from the same locality as the original types to serve as a
neotype.

For instance:

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  Original Type Material: All specimens of Butterflyusextinctus are lost or destroyed. In this context:
 Neotype: A specimen collected in 2020 from the same locality where the original
types were collected. This specimen is chosen to serve as the new definitive reference  Cotypes: Include all specimens that were originally part of the series used to describe
for Butterflyusextinctus. Amphibiusnovus. These could be syntypes, paratypes, or any other specimens from
the same series if the original description did not designate a holotype.
The selection process for a neotype involves:

1. Choosing a Specimen: Selecting a specimen that is representative of the species and The term cotype is less commonly used today, as modern taxonomy often relies on more
matches the original description. specific terms like holotype, syntype, paratype, and neotype to describe type specimens.
2. Documenting the Choice: Providing a clear and detailed rationale for selecting the However, in historical contexts or when referring to multiple original specimens collectively,
neotype and ensuring that it is well-documented in the literature. the term cotype may still be relevant.

To summarize: Classification of Animal kingdom

 Neotype of Butterflyusextinctus: A newly selected specimen that replaces the lost
Animal classification allows us to better
original type material and serves as the reference for the species.
grasp their qualities and distinctions from
The designation of a neotype helps ensure that the species can be reliably identified and other organisms. Animals are the most well-
studied, even in the absence of the original type specimens. known organisms. They are classified as
part of the Kingdom Animalia, sometimes
9. Cotype: A term formerly used for syntype and sometimes (erroneously) for isotype and known as the Animal Kingdom, in scientific
paratype. This is an old term that was used loosely and is not used by today's taxonomists. terms. Let’s find out more about this well-
known Kingdom.
 The term cotype is used in taxonomy to refer to any of the specimens that were part
of the original series of specimens used to describe a species or subspecies when no
single holotype was designated.
 It encompasses both the type specimens that were originally cited in the description of
a species and any additional specimens from the same collection event.

Definition:

Cotype: Any specimen among the original series of specimens used to describe a species or
subspecies when no holotype was designated. The term can include holotypes, syntypes,
paratypes, and other specimens from the original collection.

Example:

Suppose Dr. Allen described a new species of amphibian, Amphibiusnovus, in 1950. Dr.
Allen collected several specimens from a specific swamp and included all of them in the
original description without designating one as the holotype. All these specimens are referred
to as types in the original publication, and collectively, they are called cotypes.

For example:

 Cotypes of Amphibiusnovus: Specimens #001, #002, and #003 collected from the
Classification of Animal kingdom
swamp and described together in Dr. Allen’s 1950 paper.

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 The basis of the classification of the animal kingdom issegmentation, notochord, coelom,  Animals like Annelids, Arthropods, etc., where the body can be divided into identical left and
symmetry, level of organisation, and cell organisation. In addition to the basic traits, each right halves in only one plane, exhibit bilateral symmetry.
phylum or class has a variety of other unique characteristics

Classification of Animal Kingdom is based on various fundamental features like –

1. Levels of Organisation,
2. Symmetry,
3. Diploblastic and Triploblastic Organisation,
4. Coelom development,
5. Segmentation of the body and
6. Presense or absence of Notochord.

Levels of Organisation
 Though all members of Animalia are multicellular, all of them do not exhibit the same pattern
of organisation of cells.
Diploblastic and Triploblastic Organisation
 For example, in sponges, the cells are arranged as loose cell aggregates, i.e., they
 Animals in which the cells are arranged in two embryonic layers, an external ectoderm and
exhibit cellular level of organisation. Some division of labour (activities) occur among the
an internal endoderm, are called diploblastic animals, e.g., Coelenterates. An
cells.
 In coelenterates, the arrangement of cells is more complex. Here the cells performing the undifferentiated layer, mesoglea, is present in between the ectoderm and the endoderm.
 Those animals in which the developing embryo has a third germinal layer, mesoderm, in
same function are arranged into tissues, hence is called tissue level of organisation.
between the ectoderm and endoderm, are called triploblastic animals (platyhelminthes to
 A still higher level of organisation, i.e., organ level [organ level of organisation] is exhibited
by members of Platyhelminthes and other higher phyla where tissues are grouped together to chordates).
form organs, each specialised for a particular function.
 In animals like Annelids, Arthropods, Molluscs, Echinoderms and Chordates, organs have
associated to form functional systems, each system concerned with a specific physiological
function. This pattern is called organ system level of organisation.
 Organ systems in different groups of animals exhibit various patterns of complexities.
 For example, the digestive system in Platyhelminthes (incomplete digestive system) has
only a single opening to the outside of the body that serves as both mouth and anus, and is
hence called incomplete. A complete digestive system has two openings, mouth and anus.
 Similarly, the circulatory system may be of two types: open type in which the blood is
pumped out of the heart and the cells and tissues are directly bathed in it and closed type in
which the blood is circulated through a series of vessels of varying diameters (arteries, veins
Figure: Showing germinal layers : (a) Diploblastic (b) Triploblastic
and capillaries).
Coelom
Symmetry
 Presence or absence of a cavity between the body wall and the gut wall is very important in
 Animals can be categorised on the basis of their symmetry.
classification.
 Sponges are mostly asymmetrical, i.e., any plane that passes through the centre does not
 The body cavity, which is lined by mesoderm is called coelom.
divide them into equal halves.
 Animals possessing coelom are called coelomates, e.g., Annelids, Molluscs, Arthropods,
 When any plane passing through the central axis of the body divides the organism into two
Echinoderms, Hemichordates& Chordates.
identical halves, it is called radial symmetry. Coelenterates, Ctenophores and Echinoderms
 In some animals, the body cavity is not lined by mesoderm, instead, the mesoderm is present
have this kind of body plan.
as scattered pouches in between the ectoderm and endoderm. Such a body cavity is

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 called pseudocoelom and the animals possessing them are called pseudocoelomates, e.g.,  Eukaryotic creatures are all organisms that belong to this Kingdom, according to
Aschelminthes. science.
 The animals in which the body cavity is absent are called acoelomates, e.g., Platyhelminthes.  They’re all multicellular, with a lot of cells. The cells are devoid of cell walls.
Another distinguishing aspect is that they consume in a heterotrophic mode, which
means they cannot produce their own food.

2. The Different Phyla

Kingdom Animalia is a classification system for animals. It’s further subdivided into many
phyla. These are simply classifications that group together creatures or species that share
similar traits. Aside from the Animal Kingdom’s key distinguishing qualities (eukaryotic,
multicellular, without a cell wall, and heterotrophic), each phylum comprises species with
similar characteristics. They progress from the simplest to the most complicated on the
animal classification chart.

The different phyla in the classification of animals are as follows:

Segmentation
 Phylum Porifera
 In some animals, the body is externally and internally divided into segments with a serial
repetition of at least some organs.  Phylum Coelenterata
 For example, in earthworm, the body shows this pattern called metameric segmentation and
the phenomenon is known as metamerism.  Phylum Platyhelminthes

Notochord  Phylum Nematoda

 Notochord is a mesodermally [the middle layer of cells or tissues of an embryo, or the parts
 Phylum Annelida
derived from this (e.g. cartilage, muscles, and bone)] derived rod-like structure formed on the
dorsal side [posterior] during embryonic development in some animals.  Phylum Arthropoda
 Animals with notochord are called chordates and those animals which do not form this
structure are called non-chordates, e.g., Porifera to Echinoderms.  Phylum Mollusca

 Phylum Echinodermata

Classification of Animal kingdom  Phylum Protochordata

Kingdom-Animalia  Phylum Vertebrata

1. Animal Kingdom
Phylum Porifera
 Kingdom Animalia includes species ranging in complexity from the simplest to the
most complex.  These are the most basic multicellular animals, mostly
 The microscopic creatures are at one end of this animal classification. On the other found in marine environments. Pores can be found all
hand, you see animals that you are likely to encounter in your everyday life. over the body of these species.
 For example, you and your buddies are members of the Animal Kingdom. This vast  They have a canal system that allows water, food
domain includes your beloved dog, bird, cat, and even those bothersome insects you particles, and oxygen to circulate.
encounter in the garden.

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  Tissue differentiation and division are modest in the body design. Spongilla, Sycon,  Annelids can be found in a variety of
and other forms are commonly referred to as Sponges. environments, including land, fresh water, and
even the ocean.
Phylum Coelenterata  They have three germ layers and a body that is
bilaterally symmetrical (Triploblastic).
 These organisms have a more differentiated body.  They have a real body cavity, which is a
 They are aquatic creatures. unique trait.
 A sac-like compartment exists within the body, with  The body is segmented as well, with organ
a single opening for ingestion and egestion. distinction visible. Earthworms and leeches
 These creatures are known as diploblastic because are two examples.
they contain two germ layers.=
 These creatures can be found living alone or in colonies. Jellyfish, Sea Anemone, and
Hydra are some examples.
Phylum Arthropoda
Phylum Platyhelminthes
 They are the most numerous
 Flatworms are the popular name for these creatures. species in the animal kingdom. This
Their bodies are dorsoventrally flattened. With three phylum contains the majority of insects.
germ layers, they are the first triploblastic creatures.  The term “Arthropoda” refers to
 The body is also bilaterally symmetrical, with the animals with jointed legs.
same design on both the left and right halves.  These creatures’ bodies are
Flatworms can be parasitic or non-parasitic. separated into three sections: head,
 Planaria, Liver Fluke, and Tapeworm are just a few thorax, and belly. They have a pair of
examples. compound eyes in addition to the jointed
legs.
Phylum Nematoda  The presence of an open circulatory system is another distinctive trait of these
creatures.
 These animals maintain bilateral symmetry and  Butterfly houseflies, spiders, mosquitoes, crabs, and other insects are examples.
triploblastic nature.
 The body, on the other hand, is more cylindrical Phylum Mollusca
and has not been flattened.
 The coelom in the bodily cavity is not the same  The body layers’ triploblastic nature and
as the coelom in the coelom in the coelom As a result, bilateral symmetry are also seen here.
it’s known as a faux coelom. Mollusks are a diverse group that play a
 Organs are missing, yet tissues are present. vital role in the environment.
These species have a completely straight alimentary  These creatures can be found in water
canal. environments. They might be freshwater or
 The majority of the species in this phylum are disease-causing parasitic worms. marine species.
Ascaris and Wucheria are two examples.  The body has little segmentation, and the
coelomic cavity has shrunk.
Phylum Annelida  The anterior head, ventral muscular foot, and dorsal visceral mass are the most
common divisions of the body.
 The animal’s mobility is aided by the foot. Snails, mussels, and octopuses are
examples.

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 Phylum Echinodermata The Vertebrata Phylum is divided into five classes. They are as follows:

 Phylum Echinodermata is the next  Pisces

phylum in the animal categorization system.  Amphibia
Animals with prickly skin are known as  Reptilia
echinoderms.  Aves
 They only exist in a maritime  Mammalia
environment.
 They are free-roaming creatures. Adults Conclusion
have radial symmetry, whilst larvae have bilateral symmetry.
 These creatures have a coelomic cavity and are triploblastic. They feature a unique In this world, there are millions of living organisms. There are even a few that have yet to be
water-driven tube system that aids in their movement. discovered. Animals, plants, microbes, and other living entities that are known to man are
 They have a strong exoskeleton formed of calcium carbonate as well. Starfish, sea included in this category. They’re all really diverse. However, there are some qualities that
cucumber, and sea urchin are some examples. are shared by groups of creatures, and this is what connects them.

Phylum Protochordata Invertebrates

 The protochordates are triploblastic and Invertebrates are a diverse and fascinating group of animals that lack a backbone or spinal
bilaterally symmetrical. column. They make up about 95% of all animal species on Earth. Here are some key
 They’ve got a coelom. categories and examples:
 The presence of a notochord at some point in
their life cycle is a new body feature seen in 1. Arthropods: The largest group of invertebrates, including insects, spiders,
these creatures. crustaceans (like crabs and shrimp), and myriapods (centipedes and millipedes). They
 They are known as chordates because of the have exoskeletons, segmented bodies, and jointed legs.
presence of a notochord. It is, however, 2. Mollusks: This group includes snails, clams, octopuses, and squids. Mollusks usually
sometimes rudimentary. have soft bodies and may have a hard shell for protection.
 They are only found in the sea. Herdmania and Balanoglossus are two examples. 3. Cnidarians: This group consists of animals like jellyfish, corals, and sea anemones.
They are characterized by their stinging cells, called cnidocytes, and a simple body
Phylum Vertebrata plan with radial symmetry.
4. Annelids: Segmented worms such as earthworms and leeches belong to this group.
 These are the most advanced creatures, with They have a segmented body and a true coelom (body cavity).
advanced traits such as a proper digestive system, circulatory 5. Echinoderms: This group includes starfish, sea urchins, and sea cucumbers. They
system, and so on. have radial symmetry, a water vascular system, and often a tough, spiny skin.
 Body tissues and organs are differentiated in a 6. Poriferans: Commonly known as sponges, these simple organisms filter water to
sophisticated way. obtain nutrients and lack true tissues and organs.
 These animals have an internal skeleton and a real 7. Platyhelminthes: Flatworms, including planarians, tapeworms, and flukes, fall into
vertebral column. this category. They have a flattened body and can be free-living or parasitic.

The following characteristics are shared by all chordates: Invertebrates play crucial roles in ecosystems, from pollination and decomposition to serving
as prey for other animals. Their adaptability and diversity make them key players in many
 Notochord ecological processes.
 Dorsal Nerve Cord
 Post-anal tail
 Pharyngeal slits

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Types of Invertebrates  Phylum Coelenterata

Terrestrial invertebrates involve these groups and many also have members that live in Every group has its own characteristics and adaptations.
marine environments and freshwater.

 Insects Phylum Arthropods

 Spiders  Arthropods are animals that have a segmented body.

 Worms
Their bodies are bilaterally symmetrical with a
 Slaters
strong exoskeleton made up of chitin. Arthropods
 Landhoppers
are capable of adapting to different environments
 Centipedes
quickly. Examples of Arthropods are Scorpions,
 Millipedes
Honey Bees, and Spiders.
 Velvet worms
 A beetle’s shell is called an exoskeleton and it
Freshwater and marine invertebrates involve the following groups and some of them also
have land-dwelling members. makes up for the lack of a backbone by providing
rigidity and form.
 Sea stars and sea urchins
 Anemones and corals
 Snails and slugs
 Sponges Phylum Mollusca
 Bluebottles and jellies
 These animals have an unsegmented body, unlike
 Crabs, prawns, crayfish & lobsters
arthropods. Mollusca skin consists of a mantle that
Characteristics of Invertebrates releases a shell. Their skin is soft and mostly found
By now as you know what invertebrates are, let’s get to know about their characteristics. in seawater and fresh water. Examples of Mollusca
are Octopus, Snail, and Oyster.
 All invertebrates do not have a spinal cord or vertebral column, instead, most of them
possess an exoskeleton that encompasses the entire body.
 Normally, these are tiny and don’t grow very large.
 Do not possess lungs since they respire through their skin.
 The largest invertebrate ever: An artist’s render
 Since they cannot produce their own food, Invertebrates are heterotrophic.
of a colossal squid battling a sperm whale.
 Reproduction occurs through fission.
Throughout history, there are just a handful of dead specimens found throughout the
Invertebrates involve all the animals that do not come under vertebrates group. There are
mainly four kinds of invertebrates as listed below by Phylum. world and they still remain elusive to this day.

 Phylum Mollusca
 Phylum Annelida
 Phylum Arthropods

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 like body structure, mode of reproduction, and habitat, providing a detailed understanding of
Phylum Annelida the diversity within this group.

 The group of Annelids has many worms. Their Vertebrata Meaning

bodies are segmented and consist of 3 layers and
Vertebrates are animals that have a backbone or vertebrae. Vertebrata examples
hence are called Triploblastic animals. Triploblastic
include reptiles, humans, birds, fish, mammals, and amphibians. Vertebrata are also known
refers to having 3 layers ectoderm, mesoderm, and as craniata because they possess a skull made of cartilage or bone, which is a defining
endoderm. characteristic of this group.
The size of a living vertebrate animal ranges from the frog Paedophryne amanuensis [7.7
 Examples of Annelida involve Earthworm,
millimeters] to the blue whale [108 feet]. In the Animalia kingdom, the vertebrata subphylum
Sandworm, and Leech. includes the subphylum Deuterostomia and the phylum Chordata.

Vertebrata Examples
 The biggest leech in the world: The Giant Amazon Leech Vertebrata includes a wide range of animals, each with distinct characteristics:

 Mammals: Animals like humans, elephants, and whales that have fur or hair and
Phylum Coelenterata produce milk to feed their young.
 Birds: Examples include eagles, sparrows, and penguins, characterized by feathers,
 The bodies of Coelenterates are radially beaks, and the ability to lay eggs.
 Reptiles: Such as snakes, lizards, and turtles, which have scaly skin and typically lay
symmetrical. These animals are diploblastic which
eggs on land.
means that their bodies comprise 2 layers known  Amphibians: Frogs, salamanders, and newts, which usually live both in water and on
as ectoderm and endoderm. Examples of land during different life stages.
 Fish: Including salmon, sharks, and goldfish which live in water, have gills for breathing
Coelenterates are Hydra, Jellyfish, and Coral. and are often covered in scales.

Evolution of Vertebrata
The evolution of Vertebrata is given below:
Vertebrates
 More than 500 million years ago, the earliest vertebrates resembled hagfish.
One of the ways life is classified is through the presence or absence of the vertebrate.  Other classes of fish evolved traits such as a complete vertebral column, jaws, and a
Vertebrates and invertebrates evolved from a common ancestor that was speculated to have bony endoskeleton as they evolved.
lived around 600 million years ago.  Amphibians were the first tetrapod vertebrates to live on land, as well as the first
vertebrates to evolve.
Evidence of true vertebrates began to appear 525 million years ago and ever since then,  The first amniotic vertebrates were reptiles.
vertebrates have branched off into a long lineage that includes armoured fish and giant  Endothermy, or the ability to regulate body temperature from the inside, evolved in
sauropods to woolly mammoths and modern man. mammals and birds, both of which descended from reptile-like ancestors.

Vertebrata – Definition, Classification, Characteristics, Features Vertebrata Characteristics

The major characteristics are:
Vertebrata division in the Animal Kingdom includes animals with a backbone or spinal  Jaws can be found in some vertebrates. Jawless species are classified as vertebrates.
column. Animals that belong in Vertebrata examples are such as mammals, birds, reptiles,  The notochord eventually becomes a vertebral column, with the vertebrae on the dorsal
amphibians, and fish. Vertebrata classification is based on various Vertebrata characteristics side.

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 The anatomy of vertebrates is similar, with a vertebral column, gastrointestinal tract, and  Some examples of animals belonging to Class Reptilia are Tortoise, turtles, crocodiles
spinal cord present in all vertebrates. and snakes.
 The internal skeleton helps to distribute muscle attachment nodes. Class Mammalia
 The presence of the central nervous system is an important trait in this group. The
anterior nerve tube of the spinal cord expands into the brain.  Warm-blooded: Mammals maintain a constant internal body temperature.
 Internal Fertilization: Reproduction typically involves internal fertilization and live
Vertebrata Classification birth. (Echidna is an egg-laying exception).
The Vertebrata is classified into the following classes. Let’s discuss in detail:  Four-chambered Heart: Their hearts have four chambers for efficient blood circulation.
 Mammary Glands: They possess mammary glands for producing milk to nourish their
young.
 Hair or Fur: Their bodies are covered in hair or fur for insulation and protection.
 Heterodont Teeth: They have different types of teeth specialized for various functions
(incisors, canines, molars).
 Neocortex: Their brains have a well-developed neocortex associated with higher
cognitive functions.
 Sweat Glands: They have sweat glands that help in temperature regulation.
 Oil Glands: Their skin also contains oil glands for lubrication and waterproofing.
 Diverse Habitats: Mammals occupy a wide range of habitats, from aquatic
environments (whales, dolphins) to land (kangaroos) and even aerial environments
(bats).
Class Amphibia
This class contains 4000 different species of animals that spend their larval/juvenile stages in
water and their adult lives on land. To mate and lay eggs, amphibians must return to the
water. Most adults have moist skin which helps in gas exchange in their small, inefficient
lungs. This transitional group consists of frogs, toads, newts, salamanders, and mudpuppies.

Amphibian characteristics not found in bony fish include:

 Limbs with bone girdles that are designed for walking on land.
 A tongue that can be used for both prey capture and sensory input.
 A vocalization-adapted larynx.
Class Reptilia
 Ears are designed to detect sound waves moving through the thin (in comparison to
Reptiles’ bodies are covered in scutes or scales, and the epidermal scales is shed in some
water) medium of air.
cases. There is no external pinna, and the auditory functions are performed by the tympanum.
 Eyelids that help in keeping the eyes moist.
Crocodiles are an exception in class Reptilia as they have four-chambered hearts instead of
Class Aves (Birds)
characteristic three-chambered hearts.
The Aves are members of the Animal kingdom’s phylum Chordata. It has approximately
Reptiles, unlike other vertebrates, are cold-blooded animals. 9,000 species. Aves can fly and the Aves class includes all birds. Birds are dinosaurs from a
biological standpoint (more aptly called avian dinosaurs).
 These are terrestrial animals that creep and burrow and have scales on their bodies. The
skull has a single condyle.  This group of organisms is distinguished by feathers, toothless beaks, and a rapid
 They are cold-blooded animals found in most of the world’s warmer regions. metabolic rate.
 The body is divided into four sections: the head, neck, trunk, and tail. Their skin is rough  They exhibit courtship, parental care, nest construction, and territorial behaviour.
and dry, with no glands.  Members of the Aves class also lay hard-shelled eggs.
 Few of these shed their skin scales as skin cast. Respiration is accomplished through the  Birds are warm-blooded creatures. They have excellent vision. Their forelimbs have
use of the lungs. been transformed into wings. They don’t have any teeth.

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 They have well-developed flight muscles, which help in flight. The lower and upper jaws  Some sharks, such as the massive Greenland shark, can live for hundreds of years. A
have been modified to form a beak. specimen tagged in 2016 was discovered to be at least 273 years old.
 Their hind limbs have evolved to allow them to walk, hop, perch, grasp, wade, and  These are true-jawed vertebrates with breathing, excretory, and circulatory systems.
swim. By allowing air to pass through, friction is reduced.  Poikilotherms are organisms that are unable to regulate their body temperature.
 Their spindle-shaped body reduces wind resistance. The feathers prevent heat loss and  This category contains fish with scales all over their bodies. These vertebrates are
reduce airflow. Their legs are covered in epidermal scales. oviparous, and they breathe only through their gills. Fish have two-chambered hearts and
 The endoskeleton is made up of bony structures with long hollow bones filled with air skeletons that are entirely made of cartilage.
cavities. referred to as pneumatic bones. Except for the oil gland, there are no skin
glands. General Features of Vertebrata
 The features of Vertebrata are:
Class Osteichthyes
The class Osteichthyes includes approximately 20,000 species of bony fish found in both  Endoskeleton: Vertebrates have a well-developed internal skeleton for support and
saltwater and freshwater. It is the largest vertebrate class and the class of bony fish, with structure. This can be cartilaginous or bony.
 Skull: The skull protects the brain.
skeletons that have bones rather than cartilage like sharks.
 Vertebral Column: The backbone, made of vertebrae, contains the spinal cord and
 Two main types: provides flexibility.
o Ray-finned fish (Actinopterygii): This group comprises the vast majority of External Features of Vertebrata
bony fish species. Their fins are supported by thin, bony rays. (Examples:  The vertebrate’s specialization for capturing large prey is evident in both the structure of
goldfish, salmon, tuna) the mouth and the relatively simpler structure of the pharynx, with its strong gill
o Lobe-finned fish (Sarcopterygii): This group is less diverse but has historical development.
significance. Their fins are fleshy lobes with internal bones, thought to be a  The evolution of the chordate notochord, dorsal nerve tube, and pharyngeal slits suggests
precursor to limbs in amphibians. (Examples: lungfish, coelacanth) improved swimming ability and, most likely, greater ability to capture prey.
 Gills with bony covers: Bony fish have gills for respiration, protected by bony covers  Swimming adaptations are also there which involves variations in body form as well as
called opercula. medial and lateral fins.
 Swim bladders: Many bony fish possess a swim bladder, a gas-filled internal sac that  Feeding specialization is seen again in the two basic groups of vertebrates, agnathans,
helps them control buoyancy and stay at a desired depth. and gnathostomes.
 External fertilization: Reproduction typically involves external fertilization, where Internal Features of Vertebrata
eggs are released in water and fertilized by sperm.  The endoskeleton protects the brain and spinal cord and primarily helps in trunk and tail
Class Agnatha locomotion. The endoskeleton begins as cartilage and can either remain that way or
The characteristics of class Agatha are: develop into bone.
 The cartilaginous endoskeleton of a shark or chimaerid is typically calcified to make it
 Jawless Vertebrates: Agnatha is the only living group of vertebrates without jaws.
stiffer and stronger.
 Circular Mouth: They possess a circular mouth for feeding and attachment.
 Bone is distinct but highly variable; some types of bone contain cells, while others do
 Feeding Strategies: While some species are parasitic feeders on fish, others are
not; bone can be laminar, spongy, or arranged in sheathing layers around blood channels.
scavengers.
Nervous System and Sense Organs of Vertebrata
 Examples: Hagfish and lampreys are the two main Agnatha groups.
The Vertebrata have a highly developed nervous system and sense organs.
 Lamprey Lifecycle: Lampreys hatch in freshwater, spend most of their lives there
(though some migrate to sea), and return to freshwater for reproduction.
 Sucker-like Mouth: Lampreys have a specialized mouth for attaching to prey, lacking Nervous System of Vertebrata:
true jaws.
Class Chondrichthyes  Dorsal Tubular Structure: The central nervous system (CNS) is located on the dorsal
The characteristics of class Chondrichthyes are: side of the body and has a hollow tube-like structure. This distinguishes vertebrates from
 The cartilaginous skeleton, as the name implies, distinguishes this class. Members hemichordates.
include sharks, rays, skates, and sawfish.

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 Epidermal Origin: The CNS originates from the ectoderm, the outer embryonic germ
Features Invertebrates Vertebrates
layer.
 Spinal Cord: The CNS runs along the back and is protected by the vertebral column. It
transmits signals between the brain and the rest of the body.
Reproduction Asexual and sexual Primarily sexual
Sense Organs of Vertebrata
 Paired Sensory Organs: Vertebrates have paired sensory organs for smell (nasal), sight
(optic), and balance/hearing (otic). These organs are located on the head, contributing to
Circulation Open or closed Closed
a well-developed head region.
 Chemical Reception: The nasal organs detect chemicals in the environment, similar to
taste buds.
 Complex Eyes: Eyes are the most complex sensory organs, formed from an outgrowth
Wide range, from microscopic Wide range, from small
Size planktons to large arthropods frogs to large whales
of the brain and a lens derived from the skin. They allow for vision and have varying
focusing abilities across different vertebrate groups.
 Inner Ear Development: The inner ear (otic vesicle) originates from a simple sac and
Insects, spiders, worms, molluscs, Fish, amphibians, reptiles,
becomes more complex with nerve connections. It plays a role in balance and hearing. Examples crustaceans, etc. birds, mammals
 Lateral Line System: This unique system of canals and organs detects water movement
and pressure changes, especially important for aquatic vertebrates. It can also be found
on the head and body.
Similarities between Invertebrates and Vertebrates
Difference between Invertebrates and Vertebrates
The table below gives us the points of difference between invertebrates and vertebrates: We have understood that there are differences between Invertebrates and Vertebrates. But
there are similarities also like:
Features Invertebrates Vertebrates  Both groups have the inbuilt mechanism of regulating temperature also known
as homeostasis.
 Majority of the vertebrates and all invertebrates reproduce sexually.
Backbone Absent Present  Both vertebrates and invertebrates show various adaptations and ability to evolve.

May or may not have an Have an internal skeleton

Evolutionary relationships between Animal Groups
Skeleton exoskeleton (bone or cartilage)
Understanding the evolutionary relationships between animal groups is key to
comprehending the diversity of life on Earth. Here's a broad overview of how major animal
groups are related based on evolutionary biology:
Symmetry Radial or bilateral Bilateral
1. Domain Eukarya

Nervous Simple to well-developed Highly developed All animals belong to the domain Eukarya, which means their cells have a nucleus and other
System membrane-bound organelles.

Various methods (diffusion, gills, Gills, lungs, a combination 2. Kingdom Animalia

Respiration tracheal systems) of gills and lungs
Within Eukarya, animals belong to the Kingdom Animalia. This kingdom is characterized by
multicellularity, heterotrophy (consuming other organisms for energy), and, in most cases,
the ability to move.

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3. Major Animal Phyla h. Echinodermata (Starfish, Sea Urchins)

The animal kingdom is divided into several major phyla, each representing a distinct  Characteristics: Radial symmetry (as adults), water vascular system.
evolutionary lineage. Here’s a simplified overview:  Evolutionary Note: Although they exhibit radial symmetry as adults, they are closely
related to bilateral animals (deuterostomes).
a. Porifera (Sponges)
i. Chordata (Vertebrates and their Relatives)
 Characteristics: Simple, porous body structure, mostly sessile (non-moving).
 Evolutionary Note: Considered one of the earliest branches of animals; they lack true  Characteristics: Notochord, dorsal nerve cord, pharyngeal slits, post-anal tail.
tissues and organs.  Evolutionary Note: Includes all vertebrates (fish, amphibians, reptiles, birds,
mammals) and their relatives (like tunicates and cephalochordates).
b. Cnidaria (Jellyfish, Corals, Sea Anemones)
4. Deuterostomes vs. Protostomes
 Characteristics: Radial symmetry, stinging cells (cnidocytes).
 Evolutionary Note: They have true tissues but no complex organs. They are among The animal kingdom is further divided into two major developmental pathways:
the earliest animals with a more organized body structure.
 Deuterostomes: Includes Echinodermata and Chordata. In these animals, the anus
c. Platyhelminthes (Flatworms) develops before the mouth during embryonic development.
 Protostomes: Includes Arthropoda, Mollusca, Annelida, and others. In these animals,
 Characteristics: Bilateral symmetry, unsegmented, and a simple digestive system. the mouth develops before the anus.
 Evolutionary Note: They represent an early branch of bilateral animals.
5. Evolutionary Relationships
d. Nematoda (Roundworms)
 Multicellularity and Tissue Formation: Evolved early, leading to more complex
 Characteristics: Bilateral symmetry, cylindrical body, complete digestive system. body plans.
 Evolutionary Note: They have a pseudocoelom (a body cavity not completely lined  Bilateral Symmetry: Emerged in early bilateral animals, allowing for more complex
with mesoderm). movements and body structures.
 Coelom Formation: Development of a true coelom allowed for more complex
e. Annelida (Segmented Worms) internal structures and organ systems.
 Segmented Bodies and Exoskeletons: Provided evolutionary advantages for
 Characteristics: Segmented body, true coelom (body cavity fully lined with movement and protection.
mesoderm).
 Evolutionary Note: Represent a more advanced branch of bilateral animals with The relationships among these groups are depicted in phylogenetic trees, which show the
segmentation. evolutionary pathways and common ancestors. Modern taxonomy uses molecular data (like
DNA sequences) to refine and sometimes challenge traditional classifications based on
f. Arthropoda (Insects, Arachnids, Crustaceans) physical characteristics alone.

 Characteristics: Exoskeleton, jointed legs, segmented body. Evolutionary Relationships

 Evolutionary Note: They are the most diverse and numerous animal group. The A common ancestor between two different organisms can be inferred from essential traits
development of an exoskeleton and jointed limbs is key. that they share. These similarities can be used to define evolutionary connections. In order
to establish evolutionary relationships and identify patterns amongst organisms, an
g. Mollusca (Snails, Clams, Squids)
evolutionary tree or phylogeny is crucial. The following traits are helpful in determining
evolutionary relationships:
 Characteristics: Soft body, often with a hard shell, bilateral symmetry.
 Evolutionary Note: They show significant diversity in body structure and function.  Breeding behavior

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 Geographical distribution Fossils are Helpful in Developing Evolutionary Relationships
 Cladistics
 Structural similarities  Thousands of extinct animals’ fossil remains have been found and researched by
 Biochemistry paleontologists over the years.
 This fossil record demonstrates that numerous extinct species had different forms
Evolution and Classification than any of their living relatives.
 According to the theory of evolution by natural selection, genetic variety and the  The record also illustrates how organisms changed over time in succession,
principle of the fittest lead to changes in organisms through time. allowing us to discern how they changed from one form to another.
 Modern biology is built on this notion, which is supported by data from a wide  When an organism passes away, it is typically broken down by other living things
range of scientific fields. and by weathering processes.

 Organisms can be categorized as a technique of grouping them according to  When an organism dies, certain of its body parts, especially the hard ones like
similarities. shells, teeth, or bones, are sometimes maintained because they are buried in mud or
otherwise shielded from the environment and decomposing organisms. They
 The Linnaean system, created by Swedish scientist Carl Linnaeus in the 18th eventually become petrified and are permanently preserved with the rocks they are
century, is the most popular classification scheme. lodged in.
 The Linnaean system is based on the binomial nomenclature concept, which gives  The earth was formed over 4.5 billion years ago, according to techniques like
each species a two-part name. radiometric dating, and the earliest fossils resemble creatures like bacteria and
 The genus appears in the first half of the name, and the species appears in the cyanobacteria.
second.  These microbes have fossils in rocks that date back more than 3.5 billion years. The
Fossils earliest animal fossils, which are little, soft-bodied organisms resembling worms,
 Typically, when an organism dies, its body will degrade and disappear. The body, or are from the Ediacaran fauna and are almost 700 million years old.
at least some of it, may occasionally be in an environment that prevents  The earliest vertebrate fossils indicate that they initially appeared about 400 million
decomposition, completely. years ago, while the earliest mammals arrived about 200 million years later. The
 For instance, a dead insect that is entangled in heated mud will not break down fossil record isn’t comprehensive, though.
rapidly, the mud will gradually solidify and preserve its shape. the appearance of an  Paleontologists have only managed to retrieve and study a very small portion of the
insect’s body parts. All of these traces that have been preserved of living creatures fossils that are still present on Earth, and in those few instances, the succession of
are referred to as fossils. forms has only occasionally been precisely rebuilt. The evolution of the horse is one
illustration.

Carbon Dating

 One of the most common techniques in archaeology for dating organic artifacts up
to 50,000 years old is carbon dating.
 This approach is predicated on the notion of the carbon-14 isotopes’ long-term
radiative degradation.
 Physics has shown that the pace at which radioactive compounds degrade depends
on the atomic number and mass of the atoms that are decaying.
 The ratio of radioactive isotopes to the estimated initial concentration of these
isotopes at the moment of the organism’s death can be used to calculate the
approximate age of the decaying material using this constant.

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  According to scientists, there hasn’t been much of a shift in the ratio of carbon-12
0UNIT III
to carbon-14 isotopes in the atmosphere, therefore their connection should mostly
remain unchanged. MICROBIAL DIVERSITY

DNA Sequence Determination Microorganisms, also known as microbes, are tiny living organisms that are typically
too small to be seen with the naked eye. They include a wide variety of life forms
 The nucleotide sequence of DNA is its most crucial component.
Utilizing DNA polymerase’s enzymatic properties allows for the determination of such as bacteria, archaea, fungi, protozoa, algae, and viruses. These organisms can be
DNA sequences. found in almost every environment on Earth, from soil and water to extreme
 All DNA polymerases need a primer to start the synthesis process. A single primer conditions like hot springs and deep-sea vents.
is hybridized into the DNA strand that has to be sequenced to start the sequencing
1. Types of Microorganisms:
reaction.
A. Bacteria: Single-celled organisms that can thrive in diverse environments. They
play crucial roles in nutrient cycling, including nitrogen fixation and decomposition.
B. Archaea: Similar to bacteria but with distinct genetic and metabolic characteristics.
Many archaea live in extreme environments, such as high salinity or temperature.
C. Fungi: Includes yeasts, molds, and mushrooms. They are decomposers that break
down organic matter and recycle nutrients back into ecosystems.
D. Protozoa: Single-celled eukaryotes that often feed on bacteria and other
microorganisms, playing a role in controlling microbial populations.
E. Algae: Photosynthetic organisms found in aquatic environments. They produce a
significant portion of the Earth's oxygen and form the base of aquatic food webs.
F. Viruses: Acellular entities that require a host cell to reproduce. They can infect all
types of life forms, including microorganisms themselves.

2. Role of Micro organisms in Eco system

A.Nutrient Cycling:
Decomposition: Microorganisms break down dead organic matter, releasing
nutrients back into the soil and water, which are then available for uptake by
plants and other organisms.
Nitrogen Fixation: Certain bacteria convert atmospheric nitrogen into forms
that plants can use, such as ammonia, which is crucial for plant growth.
Carbon Cycle: Microbes play a role in the breakdown of organic compounds,
affecting the global carbon cycle and influencing climate change.

B. Soil Health:

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 Microorganisms are essential for soil fertility. They help decompose organic atmospheric oxygen levels, leading to the GOE. This event transformed Earth's
material, form humus, and enhance soil structure. Symbiotic relationships, such as atmosphere from an anoxic (oxygen-poor) state to an oxic (oxygen-rich) one.
those between mycorrhizal fungi and plant roots, enhance nutrient and water Ozone Layer Formation: The increase in atmospheric oxygen eventually led to the
absorption for plants. formation of the ozone layer, which protects life on Earth from harmful ultraviolet
C. Aquatic Ecosystems: (UV) radiation.
Algae and cyanobacteria are primary producers in aquatic environments, The earliest life forms were microbial, with evidence of microbial life
forming the base of the food web and producing oxygen through photosynthesis. dating back to at least 3.5 billion years ago. These microorganisms were the
Microbes play a role in the degradation of pollutants and organic matter in water ancestors of all modern life.
bodies, maintaining water quality. Symbiotic Relationships: Symbiotic relationships are the close associations
D. Human Health and Medicine: formed between pairs of species. They come in a variety of forms, such as
The human microbiome, consisting of trillions of microorganisms, is vital for parasitism (where one species benefits and the other is harmed) and commensalism
digestion, immune function, and protection against pathogens. Microorganisms are (where one species benefits and the other is neither harmed nor helped).
used in the production of antibiotics, vaccines, and biotechnological applications.
E. Bio remediation: Microbes formed symbiotic relationships, such as the one between ancient
Certain microbes can degrade or detoxify pollutants, such as oil spills, heavy eukaryotes and bacteria, leading to the development of mitochondria and
metals, and pesticides, making them useful in cleaning up contaminated chloroplasts through endosymbiosis. This was crucial for the evolution of complex
environments. eukaryotic cells.
F. Agriculture:
Microbes are used as biofertilizers and biopesticides to promote plant growth
and protect against pests. They help in composting processes, turning organic waste
into valuable fertilizer.
Their diverse metabolic capabilities enable them to influence environmental
processes and maintain ecological balance.

I. Microbes and Earth History

Parasitism and commensalism are both types of symbiotic relationships between
Microorganisms have played a pivotal role in Earth's history, influencing its
two species, but they differ in how each species is affected:
geology, atmosphere, and the evolution of life. Microorganisms, particularly
Parasitism
cyanobacteria, were crucial in the development of Earth’s atmosphere.
One species, the parasite, benefits at the expense of the other species, the host. For
example, fleas, ticks, lice, leeches, and disease-causing bacteria and viruses are all
parasites.

Fig: cyanobacteria
Great Oxygenation Event (GOE): Around 2.4 billion years ago, cyanobacteria
began to produce oxygen through photosynthesis. This process gradually increased
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Commensalism
Decomposition: Decomposer microorganisms break down dead organic matter,
One species benefits, while the other is neither harmed nor helped. For example,
releasing CO₂ and methane (CH₄) back into the atmosphere. This process is critical
barnacles that grow on whales and orchids that grow on mango trees are both
for nutrient cycling but also contributes to greenhouse gas emissions.
examples of commensalism.

Mutualism Microorganisms have had a profound impact on Earth's geology:

It is a type of ecological interaction where two or more species benefit from each Bio mineralization: Microbes can precipitate minerals, leading to the formation of

other. geological structures such as stromatolites, which are layered sedimentary

formations created by microbial communities.

Nitrogen-fixing bacteria and leguminous plants such as clover, alfalfa, and

soybeans. These bacteria live in the roots of the plants and convert atmospheric Fig: stromatolite, fossils of earliest life on earth
nitrogen into a form that the plants can use, such as nitrates.
Microorganisms are integral to the carbon cycle and thus influence climate Weathering and Soil Formation: Microbes contribute to the weathering of rocks
regulation: and the formation of soil by breaking down minerals and organic matter, which
Carbon Fixation: Photosynthetic microbes, such as cyanobacteria and algae, creates the substrate for plant life.
convert carbon dioxide (CO₂) into organic matter, sequestering carbon and reducing Evidence of ancient microbial life is found in various geological and fossil
atmospheric CO₂ levels.
records:
Microfossils: Fossilized remains of microorganisms, such as bacteria and archaea,
have been found in ancient rocks dating back billions of years.

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 Stromatolites: These layered structures, formed by the activity of microbial mats, Microorganisms are the most abundant forms of life on Earth. They inhabit virtually
are some of the oldest evidence of life on Earth, with some dating back over 3.5 every environment, from the deepest oceans to the highest mountains, and even
billion years. extreme environments such as hot springs and the Arctic tundra.
It is estimated that there are approximately 10^30 microorganisms on Earth, including
bacteria, archaea, fungi, viruses, and protozoa.
**1.2. Diversity
Species Diversity: There are estimated to be several million species of
microorganisms, although only a small fraction have been formally described. For
example, recent estimates suggest around 1 million bacterial species alone.
Genetic Diversity: Microorganisms exhibit immense genetic diversity, often more so
Chemical Signatures: Isotopic ratios and organic biomarkers in ancient rocks than multicellular organisms, due to their high mutation rates, horizontal gene
provide indirect evidence of microbial life and their metabolic activities. transfer, and rapid reproduction.

2. Occurrence
Extremophiles
**2.1. Habitats
Extremophiles are microorganisms that thrive in extreme environments, and
Soil: Soil is teeming with microorganisms that play vital roles in nutrient cycling,
studying them provides insights into early Earth conditions:
decomposing organic matter, and supporting plant growth. Soil microbial
Analogues for Early Earth: Extremophiles living in conditions similar to those of
communities can number in the billions per gram of soil.
early Earth (such as high temperature, acidity, or salinity) help scientists understand
Water: Microbes are abundant in freshwater and marine environments. Oceanic
how early life might have survived and evolved.
microbial communities are estimated to have up to 10^6 to 10^7 cells per milliliter,
Astrobiology: Research on extremophiles informs the search for life on other
while freshwater lakes can also host millions of microorganisms.
planets and moons, as these organisms demonstrate the potential for life to exist in
Air: Airborne microorganisms include bacteria, fungi, and viruses. They can travel
harsh environments beyond Earth.
long distances, contributing to global microbial dispersal.
microorganisms have been and continue to be, fundamental to Earth's history,
Extreme Environments: Extremophiles thrive in harsh conditions such as high
shaping the planet's atmosphere, geology, and the evolution of life. Understanding
temperatures, high salinity, or acidic environments. Examples include thermophiles in
their roles provides crucial insights into the processes that have made Earth
hot springs and halophiles in salt flats.
habitable and continues to influence its ecosystems.
**2.2. Human and Animal Hosts
Human Microbiota: The human body hosts a vast number of microorganisms, with
estimates ranging from 10^13 to 10^14 microbial cells associated with the human
II. Magnitude, Occurrence and distribution of Microorganism
body, particularly in the gut, skin, mouth, and respiratory tract.
Understanding the magnitude, occurrence, and distribution of microorganisms
Animal Microbiota: Animals also have diverse microbiota that influence their health,
is crucial for comprehending their role in various environments, their impact on
digestion, and disease susceptibility.
human health, and their ecological significance.

The occurrence and distribution of microorganisms in different environments

1. Magnitude
are influenced by a variety of factors. These factors can be broadly categorized into
**1.1. Abundance
physical, chemical, biological, and anthropogenic influences.
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 example, reducing environments (e.g., sediments) support anaerobic processes like
sulfate reduction.
Factors affecting occurrence of microorganism 3. Biological Factors
1. Physical Factors Competition: Microorganisms compete for resources such as nutrients and space.
Temperature: Microorganisms have varying temperature optima. Thermophiles thrive Competitive interactions can influence microbial diversity and community structure.
in high temperatures (e.g., hot springs), psychrophiles in cold environments (e.g., Predation: Microbial predators, such as protozoa and bacteriophages, can control
Arctic regions), and mesophiles in moderate temperatures. microbial populations and influence community dynamics.
pH: The acidity or alkalinity of an environment affects microbial growth. Acidophiles Symbiosis: Symbiotic relationships, such as mutualism, commensalism, and
thrive in acidic conditions (e.g., volcanic soils), while alkaliphiles prefer alkaline parasitism, can shape microbial communities. For example, mycorrhizal fungi form
conditions (e.g., soda lakes). mutualistic associations with plant roots.
Moisture and Water Availability: Water is essential for microbial metabolism. Microbial Interactions: Microbial communities are influenced by interactions such as
Environments with high moisture content, such as wetlands, support diverse microbial cooperation (e.g., syntrophy), where different species work together to degrade
communities, while dry environments, like deserts, harbor specialized microbes complex substrates, or antagonism, where one species inhibits the growth of another
adapted to low water availability. (e.g., antibiotic production).
Oxygen Availability: Aerobic microorganisms require oxygen, while anaerobes thrive 4. Anthropogenic Factors
in oxygen-free environments. Facultative anaerobes can switch between aerobic and Pollution: Human activities can introduce pollutants (e.g., heavy metals, pesticides,
anaerobic metabolism. hydrocarbons) that affect microbial communities. Some microbes can degrade
Light: Light availability influences photosynthetic microorganisms. Phototrophs, such pollutants and are used in bioremediation.
as cyanobacteria and algae, require light for photosynthesis and are typically found in Land Use Changes: Agriculture, urbanization, deforestation, and other land use
well-lit environments. changes alter habitats and impact microbial communities by changing nutrient cycles,
Pressure: Barophiles (or piezophiles) are adapted to high-pressure environments, such soil structure, and microclimate.
as deep-sea hydrothermal vents, while most terrestrial microbes live at atmospheric Climate Change: Changes in temperature, precipitation patterns, and the frequency of
pressure. extreme weather events influence microbial distributions and activities, affecting
2. Chemical Factors ecosystem processes.
Nutrient Availability: The presence of essential nutrients, such as carbon, nitrogen, Introduction of Non-native Species: Human activities can introduce non-native
phosphorus, sulfur, and trace elements, determines microbial growth and diversity. microorganisms into new environments, potentially disrupting existing microbial
Nutrient-rich environments (e.g., compost) support high microbial activity, while communities and ecosystem functions.
oligotrophic environments (e.g., deep ocean) have lower microbial densities.
Salinity: Halophiles thrive in high-salt environments (e.g., salt flats, saline lakes), One of the most surprising characteristics of microorganisms is the range of
while most microbes prefer moderate salinity levels. physiological conditions under which they flourish. They grow across broad ranges of
Toxic Compounds: The presence of toxic substances, such as heavy metals or temperature, pH, salt concentration, and oxygen concentration. Some thrive at boiling
pollutants, can limit microbial growth. However, some microorganisms have temperatures in hot springs and at temperatures higher than 100°C in submarine vents.
developed resistance mechanisms and can even metabolize these compounds (e.g., Others are found in sea ice off Antarctica and at the North Pole. Some produce
bioremediation microbes). sulfuric and nitric acids, and many microbial species live without oxygen. Others live
Redox Potential: The oxidation-reduction potential of an environment influences the in saturated salt brines, and some are resistant to high levels of radioactivity. They are
types of metabolic processes that can occur, affecting microbial communities. For called as extremophiles.
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 Reproductive Isolation: For eukaryotes, species are often defined by their ability to
Extremophiles are microorganisms that thrive in extreme environments, and studying interbreed and produce viable offspring. This concept is less applicable to microbes,
them provides insights into early Earth conditions. especially bacteria and archaea, which reproduce asexually through binary fission or
Extremophiles are of various category. They are budding.
1.Acidophile: an organism living in extreme acidic condition (pH 3 or below) 2. Genetic and Molecular Concepts
2.Alkaliphile: an organism living at extreme alkaline (pH 9.0 and above) condition. Genetic Similarity: For microbes, species are often defined based on genetic
3.Anaerobe: an organism living in the absence of molecular oxygen. There are two similarity. Techniques such as 16S ribosomal RNA (rRNA) gene sequencing (for
subtypes, facultative anaerobe-such type can tolerate anoxic and oxic conditions. bacteria) or whole-genome sequencing allow scientists to compare genetic material
Obligate anaerobe will die in the presence or even low level of oxygen. and determine relatedness.
4.Capnophile: organism grow in high concentration of carbondioxide. Operational Taxonomic Units (OTUs): In microbial ecology, OTUs are used to
5.Cryptoendolith- organisms live in the microscopic space within rocks, pores classify bacteria and archaea based on genetic similarity. OTUs are often defined by
between aggregate grains. They are otherwise called as endolith. thresholds of genetic divergence, such as 97% similarity in 16S rRNA sequences.
6.Halophile: Organism can live in an extreme concentration of dissolved salts. 3. Phenotypic Characteristics
7.Hyperpiezophile: organism can live in extreme pressure condition. Biochemical Tests: Microbial species can also be differentiated based on biochemical
8.Hyperthermophile/ thermophile: organism live in extreme temperature condition. and physiological traits, such as metabolic capabilities, growth conditions, and
9.Hypolith: Organism lives underneath rocks in cold deserts. enzyme activities. Morphological Features: Although less common, some species are
10. Metallotolerant: organism are able to live in high level of dissolved heavy distinguished by unique morphological features, especially in fungi and protozoa.
metals in solution condition. 4. Species Concept for Bacteria and Archaea
11.Oligotroph : organism grow in nutritionally limited environment. Species Definition: The definition of a bacterial or archaeal species typically involves
12.Osmophile: Organism live in high sugar concentration condition. a combination of genetic, phenotypic, and ecological factors. For example, the
13.Radioresistant: organism capable of resisting high level of ionization radiation International Code of Nomenclature of Prokaryotes defines a bacterial species as a
including UV, nuclear radiations. group of strains with a high degree of similarity in their core genome, and they share a
14.Xerophile: organism can live in area of extreme low water availability. common ecological niche.
Genome-Based Definition: The Genome-Based Species Concept (GBSC) proposes
III. Concept of Species that bacterial species can be defined based on genome similarity thresholds. For
The traditional Biological Species Concept is not fully applicable to instance, genomes with average nucleotide identity (ANI) values above a certain
microorganisms due to their asexual reproduction, horizontal gene transfer, and high threshold (usually around 95-96%) are often considered the same species.
genetic diversity. Instead, microbial species are often defined using genetic, 5. Horizontal Gene Transfer
ecological, and phylogenetic criteria. These alternative approaches provide a more Genetic Exchange: Microbes frequently exchange genes through horizontal gene
accurate and practical framework for classifying and studying the vast diversity of transfer (HGT), which complicates the concept of species. HGT can blur the lines
microbial life. between species, as genes can be transferred between organisms across different
1. Traditional Species Concept species boundaries.
Morphological Traits: In many organisms, species are traditionally defined based on 6. Eukaryotic Microbes
morphological traits. However, for microbes, this approach is often limited because Protozoa and Fungi: For eukaryotic microbes such as protozoa and fungi, species
many bacteria and archaea are too small or too similar in appearance to distinguish definitions often involve a combination of genetic, morphological, and ecological
easily.
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characteristics. Molecular tools like DNA sequencing and phylogenetic analysis play Genetic Relatedness: Phylogenetic analysis based on genetic similarities helps to
a key role in defining and distinguishing species. determine evolutionary relationships and classify microorganisms into taxonomic
7. Ecological and Evolutionary Perspectives groups.
Ecological Niches: In microbial ecology, species can be defined by their ecological
roles and niches. Different strains or species may occupy specific environments or 5. Ecological Characteristics:
have unique interactions with other organisms. Habitat Preferences: Microorganisms can be classified based on their preferred
Evolutionary Relationships: Evolutionary relationships, revealed through ecological niche (e.g., soil microbes, aquatic microbes).
phylogenetic analysis, help define microbial species by showing how closely related Tolerance to Environmental Conditions: Classification may consider adaptations to
different microbes are. extreme conditions (e.g., thermophiles, halophiles).
6. Pathogenicity and Host Specificity:
Criteria for classifying microorganisms Pathogenic Properties: Some microorganisms are classified based on their ability to
Classification of microorganisms involves several criteria, which can vary depending cause disease in specific hosts (e.g., pathogens, opportunistic pathogens).
on the specific group of microorganisms being studied. Here are some general criteria Host Range: Host specificity may also be a criterion for classification (e.g.,
commonly used for the classification of microorganisms: host-specific pathogens, zoonotic pathogens).
1. Morphological Characteristics: 7. Phenotypic Characteristics:
Cell Shape and Size: Microorganisms can be classified based on their shape (e.g., Antigenic Properties: Immunological methods can be used to classify microorganisms
cocci, bacilli, spirilla) and size. based on their antigenic profiles (e.g., serotyping of bacteria).
Cell Arrangement: Some microorganisms exhibit characteristic arrangements (e.g., 8. Molecular Characteristics:
pairs, chains, clusters). Ribosomal RNA Sequencing: Phylogenetic studies often utilize 16S rRNA (for
2. Physiological Characteristics: bacteria) or ITS (for fungi) sequences to determine evolutionary relationships.
Nutritional Requirements: Microorganisms can be classified based on their ability to Whole Genome Analysis: Advances in genomics allow for comprehensive analysis of
utilize different sources of carbon, energy, and other nutrients (e.g., heterotrophs, entire genomes, aiding in classification and identification.
autotrophs). 9. Evolutionary Relationships:
Metabolic Pathways: Differences in metabolic processes such as fermentation, Phylogenetic Analysis: Microorganisms are classified based on their evolutionary
respiration, and photosynthesis can be used for classification. relationships, which are inferred from molecular data and other characteristics.
3. Biochemical Characteristics: These criteria are not mutually exclusive, and multiple criteria are often used in
Enzyme Activities: Microorganisms can be differentiated based on their ability to combination to classify microorganisms accurately. Advances in molecular biology
produce specific enzymes (e.g., amylase, protease). and genomics have significantly enhanced our ability to classify microorganisms with
Biochemical Tests: Various biochemical tests can be employed to identify and classify greater precision and accuracy.
microorganisms (e.g., sugar fermentation tests).
4. Genetic Characteristics: 4. Classification of microorganism
Genome Sequence: Genetic information, including DNA sequence data obtained Criteria for classification of microorganisms are the complexity of cells
through methods like 16S rRNA sequencing (for bacteria) or ITS sequencing (for structure, body organization, the mode of nutrition, life style, and phylogenetic
fungi), is increasingly used for precise classification. relationship.
The science of classifying organisms is called taxonomy and the groups
making up the classification hierarchy are called taxa. Taxonomy consists of
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classifying new organisms or reclassifying existing ones. Microorganisms are Photosynthetic autotrophs: This includes blue-green algae or cyanobacteria. They
scientifically recognized using a binomial nomenclature using two words that refer to contain chlorophyll ‘a’ similar to green plants, and perform photosynthesis. Some
the genus and the species. The names assigned to microorganisms are in Latin. The cyanobacteria are also capable of fixing atmospheric nitrogen.
first letter of the genus name is always capitalized. Classification of microorganisms E.g. Nostoc and Anabaena
has been largely aided by studies of fossils and recently by DNA sequencing. Chemosynthetic autotrophs: These microorganisms utilise energy derived from the
Methods of classifications are constantly changing. The most widely employed oxidation of inorganic substances such as nitrates, ammonia, sulphur, etc. and produce
methods for classifying microbes are morphological characteristics, differential ATP. These organisms play an important role in nutrient recycling.
staining, biochemical testing, DNA fingerprinting or DNA base composition, E.g. purple sulphur bacteria.
polymerase chain reaction, and DNA chips. Heterotrophs: They are widely distributed and play a key role in the ecosystem as
decomposers. They play a significant role in our lives. They are used for the industrial
Microorganisms are prokaryotic, such as bacteria, archaea,etc., as well as eukaryotic, production of antibiotics, organic acids, etc. They also act as nitrogen-fixers, e.g.
such as protozoa, algae, fungi, etc. Rhizobium in the root nodules of legumes. Some bacteria are pathogenic to plants and
Microorganisms can be classified based on the five kingdom classification. animals causing various diseases, e.g. cholera, tuberculosis, typhoid, botulism,
tetanus, citrus canker, fire blight of apple, etc.
I. Bacteria (Monera) b. Archaebacteria
As per the Five Kingdom Classification, bacteria are classified in the kingdom They can thrive in extreme environmental conditions. They have different cell wall
Monera. It includes Eubacteria and Archaebacteria. They are all unicellular, have a compositions, which enable them to survive in harsh conditions. The cell membrane
prokaryotic cell which is devoid of a membrane-bound nucleus, and other organelles of archaea is ether-linked as compared to ester-linked in bacteria. They are further
such as endoplasmic reticulum, mitochondria, Golgi bodies, etc. classified into three main groups:
Bacteria are the most abundant microorganisms and are present almost everywhere. Methanogens – They are found in marshy areas. They are found in the gut of many
They are classified as Gram-positive and Gram-negative, based on the Gram’s ruminating animals and are utilised for the commercial production of methane
staining pattern. This is one of the major criterion for distinguishing bacteria (biogas).
Halophiles – They are found in extreme salty areas.
Based on the shape of the cell, bacteria are classified into four main groups that are as Thermoacidophiles – They can tolerate extreme temperatures and low pH. They are
follows: found in hot springs.
Coccus or cocci (spherical)
Bacillus or bacilli (rod-shaped)
Spirillum or spirilla (spiral)
Vibrium or vibrio (comma-shaped)

a. Eubacteria
They are true bacteria. They have a rigid cell wall and may contain flagella. They are Virus
autotrophic as well as heterotrophic. Bacteria reproduce by binary fission and DNA A virus is an infectious microbe consisting of a segment of nucleic acid (either DNA
transfer. Some bacteria produce spores under unfavourable conditions. Mycoplasma or RNA) surrounded by a protein coat. A virus cannot replicate alone; instead, it must
does not contain a cell wall. infect cells and use components of the host cell to make copies of itself.
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The classification of viruses, including those that infect microorganisms, follows a Class II: Single-stranded DNA (ssDNA) viruses
structured system that considers their genetic material, replication mechanisms, and Example: Parvoviruses
other structural features. Here’s a detailed overview of how viruses are classified: Class III: Double-stranded RNA (dsRNA) viruses
Example: Rotaviruses
1. Classification Systems Class IV: Single-stranded RNA (ssRNA) viruses with positive sense (can act as
1.1. International Committee on Taxonomy of Viruses (ICTV) mRNA)
The ICTV is the primary authority responsible for the classification and naming of Example: Picornaviruses
viruses. The ICTV system classifies viruses based on several criteria: Class V: Single-stranded RNA (ssRNA) viruses with negative sense (needs to be
converted to positive sense before translation)
Type of Nucleic Acid: Viruses are categorized by their nucleic acid content, which Example: Influenza viruses
can be DNA or RNA, and further divided based on whether the nucleic acid is Class VI: Single-stranded RNA viruses with a DNA intermediate
single-stranded (ss) or double-stranded (ds). This is fundamental in the classification (reverse-transcribing viruses)
process. Example: HIV (a retrovirus)
Class VII: Double-stranded DNA viruses with a reverse-transcribing intermediate
Genome Structure: The genome of the virus can be linear, circular, or segmented. The Example: Hepadnaviruses
structure of the genome influences how the virus replicates and is a key classification 2. Specific Virus Classification
criterion. 2.1. Bacteriophages (Phages)
Viruses that infect bacteria, known as bacteriophages or phages, are classified based
Capsid Symmetry: The capsid, or protein shell of the virus, can have different on:
symmetrical shapes, such as icosahedral, helical, or complex. The symmetry of the Morphology: Phages can be classified by their shape (e.g., tailed, non-tailed) and
capsid is another important classification factor. structure (e.g., icosahedral, helical).
Nucleic Acid Type: Similar to other viruses, phages are categorized by their nucleic
Envelope: Some viruses have an outer lipid envelope derived from the host cell acid type (DNA or RNA) and whether it is single-stranded or double-stranded.
membrane, while others do not. The presence or absence of an envelope affects virus
classification. Life Cycle: Phages are also classified based on their life cycle, distinguishing between
lytic phages (which cause the host cell to lyse) and lysogenic phages (which integrate
Replication Mechanism: The process by which the virus replicates within the host cell their genome into the host's genome).
can also be a classification criterion, such as whether it uses reverse transcription or
not. Plant Viruses
Plant viruses are classified based on:
1.2. Baltimore Classification System
The Baltimore classification system groups viruses based on their replication strategy Nucleic Acid: Plant viruses can be DNA or RNA viruses, with various structural types
and type of nucleic acid. It divides viruses into seven classes: and replication mechanisms.

Class I: Double-stranded DNA (dsDNA) viruses Symmetry and Shape: They can be classified by the shape of their capsid (e.g.,
Example: Herpesviruses helical, icosahedral).
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2.3. Animal Viruses **1.1. Amoebozoa
Animal viruses are classified similarly to other viruses, based on:
Movement: Amoebas move using pseudopodia, which are temporary
projections of the cell body.
Nucleic Acid: Whether they are DNA or RNA viruses, and the nature of their strands
(single or double). Characteristics: They often have an amorphous shape and can engulf food
through phagocytosis.
Capsid Structure: The shape of the protein shell (capsid) and the presence or absence Examples: Amoeba proteus, Entamoeba histolytica (causes amoebic
of an envelope. dysentery).
**1.2. Ciliophora
3. Virus Taxonomy
Movement: Ciliates move using numerous short, hair-like structures
Viruses are classified into families, genera, and species. For example:
called cilia.
Family: Herpesviridae Characteristics: They have a complex cell structure with specialized
Genus: Herpes simplex virus organelles, such as the macronucleus and micronucleus.
Species: Human herpesvirus 1 (HSV-1) Examples: Paramecium caudatum, Balantidium coli (causes
Each level of classification provides more specific information about the virus's
balantidiasis).
characteristics and its relationship to other viruses. The taxonomy helps scientists
**1.3. Flagellata (or Zoomastigina)
understand the virus’s biology, epidemiology, and potential methods for treatment and
prevention. Movement: Flagellates move using one or more long, whip-like structures
called flagella.
Characteristics: They often have a more streamlined shape and can have
one or more flagella.
Protozoa Examples: Trypanosoma brucei (causes sleeping sickness), Giardia
Protozoa are single-celled eukaryotic organisms that are classified based lamblia (causes giardiasis).
on their modes of movement, morphology, and life cycles. The **1.4. Sporozoa (Apicomplexa)
classification of protozoa is complex due to their diverse forms and Movement: Sporozoans do not have specialized structures for movement
behaviors. Here’s a detailed overview of how protozoa are classified: but may have a complex life cycle with multiple stages.
Characteristics: They are often intracellular parasites with complex life
1. Traditional Classification cycles involving both sexual and asexual reproduction.
Traditionally, protozoa were classified into four major groups based on Examples: Plasmodium falciparum (causes malaria), Toxoplasma gondii
their method of locomotion. This classification is still used in many (causes toxoplasmosis).
contexts, although modern taxonomy incorporates additional molecular 2. Modern Classification
and genetic data:
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Modern protozoan classification incorporates genetic and molecular data 3. Ecological and Medical Importance
to refine our understanding of protozoan diversity. Here are some updated Protozoa play diverse ecological roles, such as decomposers, predators,
groups based on molecular phylogenetics: and parasites. Understanding their classification helps in studying their
interactions with other organisms, their roles in ecosystems, and their
**2.1. Amoebozoa impact on human health.
Subgroups: This group includes the traditional amoebas and slime molds. Free-living Protozoa: Important for nutrient cycling in ecosystems.
Notable Features: They exhibit a range of forms from free-living amoebas Parasitic Protozoa: Causes various diseases in humans and animals,
to complex slime molds with multicellular stages. including malaria, amoebic dysentery, and giardiasis.
**2.2. Ciliophora
Subgroups: Includes various ciliates, which can be free-living or 5. Fungi
parasitic. Fungi are separated into a different kingdom. They are heterotrophic and have a rigid

Notable Features: They possess cilia for movement and feeding, and cell wall. They are parasites or saprotrophs. Fungi are microscopic, as well as quite
big in size. They are cosmopolitan and grow in warm, humid places. A unicellular
exhibit diverse forms and behaviors.
fungi – yeast, is used for the industrial production of bread and alcoholic beverages.
**2.3. Excavata
Penicillium is used for the production of antibiotics. Some fungi cause diseases in
Subgroups: This group includes several diverse protozoa with unique plants and animals, e.g. wheat rust (Puccinia), Candida albicans causing fungal
feeding grooves and flagella. infection in humans.
Notable Features: It encompasses flagellates such as Trypanosoma and
Giardia, and often has distinctive cellular structures. 5.1. Classification Criteria
Fungi are classified into different taxonomic groups primarily based on the following
**2.4. Apicomplexa
criteria:
Subgroups: Includes various parasites with complex life cycles.
1. Morphological Characteristics: This includes the physical appearance and
Notable Features: They have an apical complex used to invade host cells, structure of the fungi, such as the shape, size, color, and arrangement of their
and can cause significant diseases. reproductive structures (spores, fruiting bodies). Morphological features are often the
**2.5. Rhizaria initial criteria used for identification and classification.

Subgroups: Includes amoebas with thread-like pseudopodia and certain 2. Reproductive Structures: The mode of reproduction is a key criterion. Fungi
reproduce through various structures like spores, sporangia, conidia, and fruiting
other protozoa.
bodies (such as mushrooms). The type and arrangement of these reproductive
Notable Features: They often have skeleton-like structures, such as tests
structures help distinguish between different groups of fungi.
or shells. 3. Biochemical and Physiological Characteristics: Differences in biochemical and
**2.6. Alveolata physiological traits, such as metabolic pathways, enzymatic activities, and cell wall
Subgroups: Includes ciliates, dinoflagellates, and apicomplexans. composition, are used for classification. For example, some fungi produce distinctive

Notable Features: They share a common feature of alveoli, which are secondary metabolites (like antibiotics or toxins) that can aid in classification.

membrane-bound sacs beneath the cell membrane.

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4. Genetic Analysis (Molecular Phylogeny): With advancements in molecular Colony Morphology: Describing the appearance of the fungal colony in terms of
biology, genetic analysis, particularly sequencing of specific genes or whole genomes, texture, color, elevation, margin, and any pigment production.
has become a powerful tool for fungal classification. Comparing DNA sequences 3. Biochemical and Physiological Tests:
allows scientists to determine evolutionary relationships and classify fungi based on Carbon Source Utilization: Testing the ability of the fungus to utilize different carbon
their genetic similarities and differences. sources (sugars, alcohols) for growth.
5. Ecological Roles and Habitats: Fungi exhibit a wide range of ecological roles and Nitrogen Source Utilization: Testing the ability of the fungus to utilize various
habitats, such as saprotrophs (decomposers), pathogens, mutualists (symbionts), and nitrogen sources (ammonium salts, amino acids).
endophytes. Classification may take into account ecological preferences and Other Metabolic Activities: Assessing enzymatic activities (e.g., production of
adaptations to specific environments. specific enzymes like cellulases or proteases) and physiological responses (e.g.,
6. Life Cycle Characteristics: Understanding the life cycle of fungi, including modes tolerance to pH or osmotic stress).
of reproduction (sexual and asexual), spore formation, and stages of development, 4. Genetic and Molecular Techniques:
helps in their classification. Some fungi have complex life cycles involving multiple DNA Sequencing: Using PCR (Polymerase Chain Reaction) and sequencing methods
stages or hosts. to analyze specific genomic regions (e.g., ITS region, LSU or SSU rRNA genes) for
7. Morphogenetic Development: This refers to the development and differentiation of accurate species identification and phylogenetic analysis.
fungal structures during growth and reproduction. The study of morphogenesis helps Molecular Markers: Utilizing specific molecular markers or probes for identifying
in understanding how fungi form and organize their structures, aiding in fungal species or detecting specific genetic sequences (e.g., species-specific primers).
classification. 5.Serological Methods:
molecular techniques such as DNA sequencing,and phylogenetic analysis, Using antibodies or antigens specific to fungal cell wall components or proteins to
have significantly advanced our understanding of fungal diversity, evolution, and identify and differentiate fungal species through immunological assays.
taxonomy. 6. Staining Techniques:
Lactophenol Cotton Blue (LPCB) Stain: Used for mounting and staining fungal
5.2. Criteria for identifying fungi structures on microscope slides, enhancing visibility and aiding in morphological
The identification of fungi involves several criteria and methods, which can vary identification.
depending on the fungal group and the available resources in a laboratory setting. Other Stains: Such as Gram staining, periodic acid-Schiff (PAS) stain, or India ink
1. Morphological Characteristics: preparation, depending on the fungal structure and the information needed.
Macroscopic Features: These include visible traits such as colony morphology (color, 7. Ecological and Environmental Considerations:
texture, shape), growth patterns (radial or filamentous), and appearance of fruiting Considering the ecological niche of the fungus, including its natural habitat,
bodies (like mushrooms or conidiophores). association with specific hosts (if applicable), and environmental factors influencing
Microscopic Features: These include characteristics observed under a microscope, its growth and survival.
such as the shape, size, and arrangement of spores, hyphae (including septation and 8. Taxonomic Keys and Databases:
branching patterns), and specialized structures like conidia, basidia, or asci. Using taxonomic keys, atlases, and databases (e.g., fungal databases like GenBank,
2. Culture Characteristics: MycoBank) to compare observed characteristics with documented species
Growth Conditions: Observing how the fungus grows on different media (e.g., agar descriptions and molecular data.
plates) under various temperatures and light conditions. 5.3. Classification
Growth Rate: Monitoring the rate at which the fungus grows and colonizes the Fungi are classified into four main classes based on their morphology and method of
substrate. spore formation. They are:
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 1. Phycomycetes – They are characterised by the presence of coenocytic methods. The traditional microbial community analysis method is based on microbial
mycelium. Spores are produced endogenously in the sporangium, e.g. isolation and pure culture, and the community structure is understood through
Rhizopus, Mucor, etc. microscopic observation and physiological and biochemical characteristics study of
2. Ascomycetes – They are commonly known as sac-fungi. The mycelium is pure microorganisms, and several non-culture methods are gradually developed in
branched and septate. The asexual spores are produced exogenously on response to the limitations of culture methods to study the types and quantities of
conidiophores and sexual spores are produced endogenously within asci. E.g. microorganisms. These methods are broadly classified as biochemistry, physiology,
Penicillium, Saccharomyces (yeast), Aspergillus, Claviceps and Neurospora, etc.
etc. 1. Microscopy Techniques
3. Basidiomycetes – Asexual spores are not formed. The basidiospores are Light Microscopy: Used for observing stained or unstained cells, this technique
exogenously produced. E.g. Puccinia (rust), mushrooms, Ustilago (smut), etc. provides information about the morphology and abundance of microorganisms.
4. Deuteromycetes – Commonly called imperfect fungi due to absence of sexual Fluorescence Microscopy: Uses fluorescent dyes or antibodies to label specific
stage in the life cycle. Most fungi are decomposers and help in nutrient microorganisms or cellular components, allowing for their detection and localization.
recycling. E.g. Colletotrichum, Alternaria and Trichoderma. Electron Microscopy: Provides high-resolution images of microorganisms, useful for
detailed structural studies. Types include Transmission Electron Microscopy (TEM)
and Scanning Electron Microscopy (SEM).
7. Chemical and Biochemical Methods of Microbial Diversity Analysis 2. Culture-Based Methods
Selective Media: Growing microorganisms on specific media that support the growth
Microbial diversity refers to the variation of many different types of microorganisms of particular types of microbes while inhibiting others.
in a collective community and the relative abundance among them.It is necessary to Enrichment Cultures: Techniques that create conditions favorable for the growth of
study microbial diversity for the following reasons. specific microorganisms, allowing them to be isolated from complex samples.
(1) The study of microorganisms in extreme environments not only enables us to 3. Molecular Methods
understand and explore the strategies and limits of life, but also provides resources for Polymerase Chain Reaction (PCR): Amplifies specific DNA sequences to detect and
the development and utilization of extraordinary substances; quantify microorganisms. Variants include:
(2) Microorganisms can be used to monitor environmental changes, and their Quantitative PCR (qPCR): Measures the quantity of DNA, providing data on
populations usually respond rapidly to environmental conditions, thus serving as good microbial abundance.
records of environmental changes in a region or history; Reverse Transcription PCR (RT-PCR): Converts RNA into DNA to study gene
(3) Microorganisms play an important role in the conservation and restoration biology expression in microbes.
of higher organisms. Metagenomics: Involves sequencing the collective genomes of microbial communities
(4) Microbes serve as models for elucidating the principles of ecological and from environmental samples, providing a comprehensive view of microbial diversity
biological evolution. With the development of various microbial diversity analysis and functions.
methods, we will be able to better study microbial diversity and apply it to life, 16S rRNA Gene Sequencing: Targets the 16S ribosomal RNA gene, which is highly
production, environment and other aspects. conserved among bacteria and archaea, to identify and classify microorganisms.
Metatranscriptomics: Sequencing of RNA to study the active gene expression profiles
7.1. Methods for microbial diversity studies of microbial communities.
Methods for studying microbial diversity have been developed over the years Metaproteomics: Analyzing the protein composition of microbial communities to
and can be divided into traditional research methods and modern molecular biology understand their functional activities.
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Metabolomics: Profiling the metabolites produced by microbial communities to gain
insights into their metabolic activities.
4. Environmental Sampling Techniques
Soil Sampling: Collecting soil samples at various depths and locations to study soil eDNA: Involves collecting and analyzing DNA from environmental samples (soil,
microbial communities. water, air) to detect the presence of microorganisms without the need for direct
Water Sampling: Collecting water samples from different aquatic environments sampling or cultivation.
(rivers, lakes, oceans) to analyze microbial content. These methods, often used in combination, allow scientists to comprehensively study
Air Sampling: Capturing airborne microorganisms using filters or impactors to study the occurrence, distribution, and ecological roles of microorganisms in various
the distribution of microbes in the atmosphere. environments, enhancing our understanding of microbial diversity and their impact on
5. Fluorescent In Situ Hybridization (FISH) ecosystems.
FISH: Uses fluorescently labeled probes that bind to specific DNA or RNA sequences
within intact cells, allowing for the visualization and identification of microorganisms
in their natural habitats.
6. Stable Isotope Probing (SIP)
SIP: Involves incubating environmental samples with substrates labeled with stable
isotopes (e.g., ^13C, ^15N). Microorganisms that metabolize the labeled substrates
incorporate the isotopes into their biomolecules, which can then be detected and
analyzed.
7. Flow Cytometry
Flow Cytometry: Uses lasers to analyze the physical and chemical properties of
microorganisms in a fluid stream. It can rapidly measure cell size, complexity, and
fluorescence, enabling the detection and sorting of different microbial populations.
8. Bioinformatics and Computational Tools
Sequence Analysis: Using bioinformatics tools to analyze DNA, RNA, and protein
sequences, providing insights into microbial diversity, phylogeny, and functional
potential.
Microbial Community Profiling: Computational methods to analyze high-throughput
sequencing data, revealing the composition and structure of microbial communities.
9. Microelectrodes and Biosensors
Microelectrodes: Measure chemical gradients (e.g., oxygen, pH) in microbial habitats,
providing information about microbial metabolic activities.
Biosensors: Devices that detect specific microbial metabolites or activities, often used
for real-time monitoring of environmental conditions.
10. Environmental DNA (eDNA)

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