Invertebrate Gallery of Indian Museum
Invertebrate Gallery of Indian Museum
Invertebrate Gallery of Indian Museum
SUBKINGDOM: PROTOZOA
THE GRAND ORIGIN OF LIFE: Our life started with a single cell and
started releasing oxygen. With the accumulation of oxygen in the
atmosphere, the beginning life started millions of years ago. The
first organisms formed are called Protists and among them, which
can move are placed under Protozoa. Some of them, like plants,
have chloroplasts in their body.
PROTOZOA DIORAMA
Protozoans show the following basic features :
Microscopic, unicellular and eukaryotic organisms.
Presence of structures for locomotion (pseudopodia, flagella
etc.)
Chlorophyll may or may not be present.
Reproduction is either sexual or
asexual; asexual binary reproduction occurs by fission, multiple
fission, budding or sporulation and sexual reproduction occurs
by gamete formation or conjugation.
The following specimens were observed and studied in the gallery:
1. Elphiduium sp.
2. Entamoeba histolytica
PHYLUM PORIFERA
GENERAL CONCEPTS ON PORIFERA
Characters:
Body consists of several interconnected vase-shaped unit
or cylinders.
The distal or free end of each cylinder has a single large
opening called OSCULUM or EXHALENT or EXCURRENT
PORE, guarded by upstanding collar of monaxon spicules.
Body is externally covered by a thin dermal epithelium or
ectoderm.
Branched and colonial sponge whose body surface is
perforated by numerous inhalant pores called ostia.
HABITAT: Sycon ciliatum is a small, marine sponge found attached
by a sticky secretion to some submerged solid objects like rocks,
shells of mollusks and corals. It is found in shallow water up to a
depth of 300 feet where waves provide the animal with plenty of
food and well oxygenated water.
2. SPECIMEN: Neptune’s cup
SCIENTIFIC NAME: Cliona patera (Hardwicke,1822)
REASON FOR SUCH NAMING: Among the larger known
sponges at up to a meter in height and width, the common
name Neptune’s Cup refers to its characteristic wine glass
shape and the Roman God Of the sea.
SYSTEMATIC POSITION
(According to Ruppert and Barnes,1994)
Phylum Porifera
Class Demospongiae
Genus Cliona
Species Cliona patera
CHARACTERS:
Body becomes free large vase shaped or large cup
shaped.
Large osculum is present at the anterior end.
The posterior end has a root like process in the form of a
stalk.
AMAZING FACTS ABOUT NEPTUNE’S CUP:
The species was thought to be extinct in the early 1900s but
living specimens were rediscovered in 2011. The most recent
living specimen of Neptune’s Cup was found off to the coast of
Singapore attached to the muddy bottom of sea floor.
A MARINE MARVEL: The ‘never-say-die’ characteristic of
Singapore’s Natural Heritage is exemplified by the Neptunes’s
Cup Sponge. It was first seen in Singapore Waters in 1822.
In MARCH 2011, during a routine survey dive, marine biologists
from DHI WATER AND ENVIRONMENT PTE. LTD. Encountered a
unique looking sponge from Southern Island of Singapore.
It was later identified by Singapore Sponge Expert, Mr. Lim
Swee Cheng.
DERMAL OSTIA
INCURRENT CANALS
PROSOPYLES
RADIAL CANALS
APOPYLES
SPONGOCOEL
OSCULUM
TO OUTSIDE
DERMAL OSTIA
INCURRENT CANALS
PROSOPYLES
FLAGELLATED CHAMBERS
APOPYLES
EXCURRENT CANALS
OSCULUM
TO OUTSIDE
CNIDARIA DIORAMA
1. MOON JELLYFISH
PHYLUM: PLATYHELMITHES
GENERAL CONCEPTS ON PHLYUM
PLATYHELMITHES:
ETYMOLOGY “PLATY” – flat, “HELMINTHES”- worms
Platyhelminthes or flatworms are a diverse group comprising of
25000 living species, that show evolutionary achievements over the
diploblasts in having a structural body plan that is based upon
bilateral symmetry and in having definite organs or system of organs.
Body is bilaterally symmetrical and dorsoventrally flattened.
They are triploblastic acoelomate animals having organ systems
that occur in the middle layer.
Digestive system has a single opening or mouth, that leads to a
well-developed gastrovascular cavity. Anus absent.
Body spaces are filled with parenchyma.
Anterior end of the body is differentiated into head.
Presence of organs for attachment.
Long and ribbon like body provides a large surface area for
reciprocal chemical exchange with the host’s gut.
Body is covered by tegument which provides protection against
the hostile chemical environment of the host.
Presence of microtriches in the body wall which helps in
absorption of foodstuff and maintaining the position of worm
in the host’s gut.
Head bears four suckers for attachment with the wall of small
intestine of the host.
Rostellum is surrounded by two rows of hooks which
strengthen the attachment with the host.
Presence of proglottids having both the male and female
reproductive organs which help in perpetuation.
PHYLUM: NEMATODA
The nematodes or roundworms constitute
the phylum Nematoda (also called Nemathelminthes). They are a
diverse animal phylum inhabiting a broad range of environments.
The basic features of all nematodes are:
Body is smooth, elongated, unsegmented and bilaterally
symmetrical.
Presence of cuticle on body surface.
Sense organs are in the form of papillae, bristles, pits or eye-
spots.
Triploblastic and pseudocoelomate organization of body
plan.
LI
FE CYCLE OF A PARASITIC ROUND WORM
1. Wuchereria bancrofti
COMMON NAME: FILARIAL WORM
Systematic Position (Ruppert and Barnes, 1994)
Phylum Nematoda
Class Secernentea
Specimen Wuchereria bancrofti
CHARACTERS: Adult-
Adult male and female worms are filiform.
Buccal capsule is absent in male, slightly developed in
female.
Male with two unequal copulatory spicules but without any
bursa.
Females are larger than males and have anterior vulva.
Head region is slightly swollen.
Presence of two circles of papillae in the head region.
PSEUDOCOELOM IN NEMATODA:
The pseudocoelom is a fluid-filled body cavity lying inside the
external body wall of the nematode that bathes the internal organs,
including the alimentary system and the reproductive system. This
body cavity is called a “pseudocoelom” because it is not fully lined by
mesodermal cells as in the true “coelomic cavity” of vertebrates. The
pseudocoelom contains the coelomocytes, provides the turgor-
hydrostatic pressure for the animal as a whole, functions as a
lubricant between tissues, and provides a medium for intercellular
signalling and nutrient transport.
PHYLUM: MOLLUSCA
MOLLUSCA DIORAMA
CHARACTERS:
Body is unsegmented with a distinct head, muscular foot and
visceral hump.
They show bilateral symmetry.
Shell is secreted by mantle, which is made up of calcium
carbonate. Shell may be external or internal.
Mantle (pallium) is a thin, fleshy fold of dorsal body wall which
encloses a space called mantle cavity.
Coelom is highly reduced. It is restricted to pericardial cavity
and to small spaces within kidneys and gonads. Spaces among
viscera (soft organs) contain blood and from haemocoel.
Eyes are present over stalks called ommatophores. Statocysts
(balancing organs) may be present. Osphradium in some
molluscs can test the chemical and physical nature of water.
1. SEA HARE
AMAZING FACTS:
Due to their lack of an outer calcareous shell, sea hares utilize cryptic
coloration, nocturnal behaviors, and ink release as defense
mechanisms. Sea hares are also distasteful to many predators due to
chemicals known as secondary metabolites which they create from
chemicals obtained from their algal diet. This chemical adaptation
also makes sea hare tissue somewhat toxic to certain animals and
fairly effective against most predators. It has been discovered that
the mucus covering the mantle also acts a deterrent against
predatory crustaceans and some fish.
2. COAT-OF-MAIL SHELL
AMAZING FACTS:
Chiton sp. Possesses a radula which enables them to
grind down food. Below radula, there lies a so-called
sub radular organ- a chemical sense organ which gives
information about suitable food in the vicinity. While
doing so, it clings hard to the ground with powerful
foot, supported by the sturdy girdle.
Absence of a strong longitudinal muscle enables to roll
in the sea floor.
In the dorsal shell plates, there are mechanical sense
organs called AESTHETES which can detect water
movement.
Inside the aesthetes, cuticular eyes are present which
are generally of 2 types- a) INTRAPIGMENTARY
CUTICULAR EYES which appears to be cup-shaped with
lens above it.
b) EXTRAPIGMENTARY CUTICULAR EYES present in the
outer skin (tegument).
Cuticular eyes enable to tell apart light and shadow on
dorsal side without removing the protective girdle from
the ground.
3. SQUID
ANNELIDA DIORAMA
1. TUBE WORM
2. Neanthes accuminata
EVOLUTIONARY SIGNIFICANCE OF
METAMERISM IN ANNELIDA
PRE
SENTATION ON METAMERISM IN ANNELIDA
CHARACTERS:
Body is segmented and covered by chitinous cuticle.
1. HORSE-SHOE CRAB
3. COCKROACH
The front legs are the shortest and the hind legs the longest,
providing the main propulsive power when the insect runs.
EXH
IBIT ON USEFUL INSECTS
PHYLUM: ECHINODERMATA
CHARACTERS:
They are the major group of deuterostome invertebrates
with pentamerous radial symmetry (body arranged in 5
parts around a central axis) and internal skeleton of
calcareous ossicles which is articulated to form skeletal
test with projecting spines or tubercles.
Presence of unique system of coelomic canals and
appendages composed of water vascular system or
ambulacral system, used for collecting and transport of
food and locomotion.
Coelom with suspended digestive tract present.
Simple reproduction characterized by external
fertilization.
DESCRIPTION OF SPECIMENS
OBSERVED
1. SPECIMEN: Red Knob Sea Star
STONE CANAL
It is a S-shaped tube which opens on the oral
side into a ring canal around the mouth. It is
also known MADREPORITE CANAL.
Inner lining of the wall bears cilia or flagella
which draw water into canal.
RING CANAL
It is a wide canal forming a ring around the
esophagus.
RADIAL CANALS They arise from the ring canal and extend
along each arm to the tip.
Radial canals lie below the ambulacral
ossicles and terminate as the lumen of
terminal tentacles.
Each radial canal in its corresponding arm
LATERAL CANALS gives out two series of narrow lateral or
podial canals along its entire length.
Each lateral canal opens into a tube foot.
The opening being provided by a valve to
prevent back flow of fluid into radial
canal.
GENERAL CHARACTERS:
Tardigrades, often called water bears or moss piglets, are near-
microscopic animals with long, plump bodies and scrunched-up
heads.
They have eight legs, and hands with four to eight claws on
each.
These tiny animals are almost indestructible and can even
survive in outer space.
Mouth is tubular and is armed with stylets which are used to
pierce the plant cells, algae or small invertebrates on which the
tardigrades feed, releasing the body fluids or cell contents.
The mouth opens into a triradiate, muscular, sucking pharynx.
Buccopharyngeal apparatus is prominent which acts as a
swallowing device.
ECOLOGICAL IMPORTANCE:
Water bears are mostly aquatic that feed on species such as
nematodes, algae, bacteria and collembolans. They act as pioneer
species by inhabiting new developing environments. This movement
attracts other invertebrates to populate that space, while attracting
predators.
AMAZING FACTS:
In many conditions, water bears can survive by going into an
almost death-like state called cryptobiosis. They curl into a
dehydrated ball, called a tun, by retracting their head and legs.
If reintroduced to water, the tardigrade can come back to life in
just a few hours.
Tardigrades have different adaptations for a wide variety of
environmental threats. In hot conditions, they release heat-
shock proteins, which prevent other proteins from warping.
Some tardigrades can form bubbly cysts around their bodies.
Like puffer jackets, the cysts allow them to survive in harsh
climates without having to revert into full tun mode.
Tardigrades are sometimes referred to as “extremophiles”, a term
used to describe super-hardy bacteria that can live on ocean vents
and other extremely inhospitable environments. Bartels clarifies that
they are not extremophiles, as they don’t really “live” and move
around in tun mode. “It’s very easy to kill them when they are out
and about in their normal environment,” .