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
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”
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
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.
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
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