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

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

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

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
oligochete
Leeches along with oligochetes; both are in the Class Clitellata
Clitellum
Coccoon
No parapodia
No head appendages
polychete

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

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

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

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
(Fig 17)
In Fiji and Samoa, palolo worms swarm
on the 7th night after the full moon
that follows the autumnal equinox!!
(October usually….)
Odontosyllis enopla

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

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

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

18. Most specialized
Tube dweller is
Chaetopterus

19. Marine annelid diversity
Specialized Taxa

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

21. Annelid Family Siboglinidae “... small but very intriguing group…”
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
Live deep in the ocean
No digestive system
Thrive in areas of high
methane or sulfur

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

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 plume heart tube
V blood vessel
trophosome
tube
Fig

27. Read Research Focus 13.1 on Chemosynthesis
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
…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: )
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:

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

29. The Sipuncula: - 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

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

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

32. “Fat inkeeper” worm is best known representative

33. Some Annelid (Echiura) vs Sipuncula Characteristics
Annelid-like
Characteristic Echiura Sipuncula
Musculature outer circular and inner longitudinal
Setae Present Absent
Metamerism early juvenile Absent
Coelom form All have schizocoelous formation
Cleavage All with spiral determinate cleavage
Larval form The trochophore is the first larva

34. Phylogeny of Annelida
Among the Eumetazoa, within the lineage of Lophotrochozoa
that includes molluscs
Annelida monophyly is widely accepted
Phylogeny within the Annelida
in turmoil over last 15 yr, but a consensus is emerging

35. Whither Polychaeta? Evolution of Clitellata? Nuclear genes and
2007
Family Capitellidae
Nuclear genes and
rDNA sequence analyses
Family Terebellidae
Whither
Polychaeta?
Evolution of
Clitellata?
Family Nerididae
Taxonomic Families
traditionally
considered to be
polychaetes