This document summarizes different taxonomic classes of annelid worms. It discusses the classes Polychaeta and Clitellata. Polychaeta includes marine bristle worms and has over 9,000 species, many of which live in tubes. Clitellata includes oligochaetes like earthworms and leeches. Specific polychaete groups are described like swimming, burrowing, and tube-dwelling worms. Specialized taxa discussed include Siboglinidae vent and whale worms. The recently classified annelid groups of Sipuncula and Echiura are also summarized.

1. Annelid Taxonomic Classes:
Polycheta
“Earthworms”
“Leeches”
“Bristle worms”
Clitellata
Over 9000 spp., mostly aquatic many live in tubes
By
Sonika Chouhan

2. Annelid Taxonomic Groups:
Previously considered sepearate phyla
“
Echiura
PogonophoraSipuncula

3. I. General Characteristics
II.Class Polychaeta
A. Basic Body Plan, Swimming, Reproduction and Development
B. Polychaete Adaptive radiation
III. Other Marine Annelids (derived polychaetes)
A. Family Siboglinida : Vent worms and whale worms
B. Echiura and Sipuncula
IV. Class Clitellata
A. Oligochaetes
B. Hirudinea
Annelida

4. Despite apparent differences the polychaetes and oligochetes
share fundamental features
Segmented body
Metamerism
Hydrostatic skeleton by
a true coelom
Complete digestive tract
Closed circulatory system
polychete
oligochete
Leeches along with
oligochetes; both are in the
Class Clitellata
Clitellum
Coccoon
No parapodia
No head appendages

5. Class Polychaeta: marine bristle worms
Prototype Errant (crawling-type) Nereis
(Fig 15.4)
Metameric condition
Prostomium peristomium
segment

6. Parapodia
Setae
or Chetae
(made of chitin)
acicula
Circulatory system
Fig 15.1-3
Parapodia
capillaries
ganglia
nephridia

7. The excretory system consists
of metanephridia that work by
selective transport
(fig 15.2)
Urine

8. Types of Skeletons in Animals
Endoskeleton
Exoskeleton
Hydrostatic skeleton
In what ways are these three types
of skeletons functionally similar?

9. Polychaete swimming simulation

10. Polychete Reproduction:
Gametes form from cells that line the coelom
Some copulate but most form Epitokes
Odontosyllis enopla
In Fiji and Samoa, palolo worms swarm
on the 7th night after the full moon
that follows the autumnal equinox!!
(October usually….)
(Fig 17)

11. • Hierarchical System of Controls
- Day length cues seasonal
reproduction
– Lunar Cycles synchronize local
spawning events
- Meteorological phenomena are
likely the final trigger to epitoky
- Complex Sex Pheromones
synchronize nuptual dance and
spawning

12. Polychete Reproduction
Is the trochophore a plesiomorphic
(ancestral) character shared by
molluscs, annelids and related phyla?

13. Metameric body plan of Nereis and
of other errants is the “basic” condition
fireworm
• Head prominent
• Crawling parapods
• Eversible pharynx
some spp. with
poison glands.

14. Swimming Polychete: Tomopteris
• Large parapods
• Transparent body
• Enormous eyes
• Active predators
Swim with paddle-like parapodia or for rapid
swimming by increasingly rapid undulations of the
body combined with parapodia

15. Burrowing Polychaete:
• Move by peristalsis
• Head streamlined
• Parapods reduced
• Deposit Feeders
“earthworm-like”

16. tube
dwellers
Feather duster
Xmas tree
Fan worms
etc.
--Tubes of
Mucus
Sand
Parchment
Calcite

17. •Movement limited
•Head reduced but
with tentacles
•Parapods small
•Passive and Active
suspension feeders
•Filter Feeders
tube
dwellers

18. Most specialized
Tube dweller is
Chaetopterus

19. Marine annelid diversity
Specialized Taxa

20. Annelid Diversity:
“
Class Echiura
Polychaeta
Family SiboglinidaeSubFamily
Vestimentifera SubFamily
Frenulata
Genus Osedax

21. Annelid Family Siboglinidae
“... small but very intriguing group…”
• Live deep in the ocean
• No digestive system
• Thrive in areas of high
methane or sulfur
Includes
Frenulate “spaghetti worms” that
feed by absorbing nutrients
Whale carcass worms: root
system absorbs bacterial
nourishment from bone marrow;
& symbiotic bacteria
Vestimentiferan giant cold seep
and hot vent worms

22. < 1mm diameter
10 - 74 cm long
(spaghetti-like worms)
Fig 13.12-13.14
Sub Family Frenulata
6-25 segments containing coelomic
compartments that are isolated from
each other by muscular septa; each
segment bears chitinous setae
opisthosoma

23. Sub Family
Vestimentifera
Large thick bodies,
up to 2 m long
vestimentum

24. Whale fall time series
Hagfish
Sleeper sharks
Polychaete worms (free living, bacterial grazers)
Vigtorniella
(Polychete)
Whale carcass worms Osedax not considered
Vestimentiferans

25. A watercolor painting shows females and males from the new marine worm species. The female worms are
illustrated both in their tubes and with a whalebone “cutaway,” to reveal their large ovisacs and extensive roots
that invade the bone. The small males live in the tubes of the females and are shown as “blowups” with their
relative positions in the tubes indicated by the dark lines. Top left: male Osedax rubiplumus. Top right: female
Osedax rubiplumus. Bottom left: male Osedax frankpressi. Bottom right: female Osedax frankpressi.

26. F. Siboglinidae
Vestimentiferans
vent worm Riftia
Fig 13.15-16
V blood vessel
plume
heart
trophosome
tube

27. …deep-sea hydrothermal vents may
help advance the understanding of
how early microbial life forms gained
a foothold in hydrothermal systems
on early Earth and potentially on
other planetary bodies.
(McCliment et al., 2005, Environmental
Microbiology 8: 114-125)
Microbiologically analogous to Archean
vent systems and may serve as models
for the origin and evolution of life in
Archean vents.
Baross ad Hoffman (1985) in
Origins of Life and Evolution of Biospheres
An alternative proposal to the “pre-biotic soup” theory…chemical
conversions that involve “transition metal sulphide catalysts” create
favorable environments for abiogenic acetate production that release
energy… acetyl-coA is the most central carbon backbone in microbial
metabolism
Martin et al., 2008, Nature Reviews 6: 804-14
Read Research Focus 13.1
on Chemosynthesis

28. The Newest Annelids
Sipuncula
Annelids
(peanut worms)
Echiura
(inn keeper
worms)

29. - Fewer than 600 species; found primarily in shallow
marine habitats; deposit/detritus feeders
- Soft bodied, with very poor fossil record, but with
distinctly protostomous embryological characters
- Best known for having teleplanic larvae
The Sipuncula:

30. The Sipuncula
Ecologically and functionally like Echiura
Instead of a proboscis a fully retractable
head region known (introvert) aids feeding

31. Muco-ciliary deposit feeders
Live in sand, mud, crevices
With scoop-shaped proboscis
Main body is large coelom
The Echiura

32. “Fat inkeeper” worm is best known representative

33. References
Google
UGC-Books
Previous Research Papers

34. Thank you