Phylum Annelida 3
Phylum Annelida 3
Phylum Annelida 3
Phylum Annelida
Terrestrial, marine,
freshwater.
Repeating segments.
Triploblastic.
True coelomates complete
gut.
Closed circulatory system.
Well developed nervous
system.
Respiratory organs.
Protostome development.
Metamerism (unspecialized)
segmentation.
One or more pairs of setae.
Phylum Annelida
Ancestral Traits
Spirobranchus giganteus
Coelomate
Christmas tree worm
Lophotrochozoan- non-molting
protostomes
Protostome
Closed circulatory system
Cephalization
Derived Traits
Segmentation
Metamerism
Septa
Setae
Bristles
Myelinated neurons
~ 40K species of annelids
Systems
Integument- epidermis is one cell layer with mucous gland
that secrete a moist cuticle.
Skeletal -hydrostatic (using coelom)
Muscle- longitudinal and circular muscles Each segments
muscles are independent of the other segments.
Digestive- complete, complex, with absorption and
digestive glands and excretory cells.
Systems (continue)
Excretory- a pair of nephridia per segment.
Respiratory -through skin, some through parapodia; tubeworms
have gills.
Circulatory- closed system, use hemoglobin as oxygen carrier.
Nervous- dorsal brain; ventral, double, solid nerve cord, with
ganglia in each segment.
Endocrine- hormones secreted by nervous system.
Reproductive-
Dioecious in Polychaeta; no special organs, posterior end becomes gonads.
Monoecious in Oligochaeta and Hirudinea; Clitellium.
Annelid Taxonomy
Phylum Annelida (an-nel-i-da)
Class Polychaeta (poly-key-ta)
Nereis, Aphrodita, Chaetopterus, Arenicola, Amphitrite
Class Clitellata
Subclass Oligochaeta (ol-e-go-key-ta)
Lumbricus, Tubifex
Subclass Hirudinea (hi-ru-din-e-a)
Hirudo, leech
Earthworm dissection
Annelid Taxomony
Class Polychaeta (many bristles) Hermodice
most numerous # species crunculata
marine
Annelid Taxomony
Class Polychaeta
Class Clitellata
Subclass Oligochaeta (few bristles)
Freshwater, marine & terrestrial
Lumbricus terrestris
Annelid Taxomony
Class Polychaeta
Class Clitellata
Subclass Oligochaeta
Subclass Hirudinea
Fixed # segments (34)
Setae absent
Hirudo
medicinalis
Annelid Phylogeny
Annelid Body Plan
Setae
Class Polychaeta
Highly specialized head
regions
Antennae
Sensory palps
Feeding appendages
Paired extensions of body
(parapodia) Bispira bunnea
sabellid worm
Often tube-dwelling
Burrow into substrate and secrete mucus/
CO3 materials
Spirobrancheus giganteus
Polychaete Anatomy
http://www.telegraph.co.uk/news/picturegalleries/picturesoftheday/9093
134/Pictures-of-the-day-20-February-2012.html
Parapodia with setae
Polychaete Anatomy (cross section)
Polychaeta
Amphitrite
Polychaeta
Parchement worm
Clade-Siboglinidae
Riftia pachyptila
Ridgea sp
Giant tube worms (Vestimentifera)
trophosome
Riftia pachyptila
http://www.bbc.co.uk/nature/life/Polychaete/by/rank/all
Polychaete Reproduction
Most are dioecious-few monoecious
Some asexually but sexually more common
Trochophore larvae
Defining characteristics
Pronounced cylindrical
glandular region of the body
= clitellum
Second largest class in the
phylum Annelida
Most spp. are earthworms,
very few are marine
27 Phylum Annelida
Polychaetes and Oligochaetes
28 Phylum Annelida
Oligochaete Anatomy
Oligochaete Anatomy
Setae: a.k.a. Bristles
Oligochaete Reproduction
Oligochaete Development
For terrestrial oligochaetes, development is direct without any
larval forms
Some aquatic oligochaetes retain a trochophore-like larval stage
Eisenia foetida
Redworm
http://www.earthlife.net/inverts/oligochaeta.html
This link shows diversity of Oligochaetes!
Earthworm Return to taxonomy
Dissection
Cross section
Aquatic Oligocheates
Subclass Hirudinea
Defining characteristics
Posterior sucker
Predominately freshwater,
but do occur in all seas and
moist soil
Leeches do not burrow,
lack parapods and setae
Clitellum only visible
during breeding
38 Phylum Annelida
Horse leech-actually feeds
on small worms
Haemopis sanguisuga
44 Phylum Annelida