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Worldwide distribution.
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Habitat: Saltwater, Freshwater, and Land.
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Marine. Found in benthic regions and on the surface.
Latin singular: Annulus
Plural: Annuli
Annelid
• Metamerization- Division of the body into a series
of repeating segments.
• What other organisms, besides those in this
phylum, are metameric?
• What is the evolutionary advantage to
metamerization?
• Oligochaeta- Earthworms
• Hirudinia- Leeches
• Polychaeta- Freshwater/Marine worms
• All Annelids (except leeches) have setae.
• Setae- Short hairs/bristles.
• Function: Anchor during movement.
Short setae: land
Long setae: aquatic
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Body segments separated by septum
Septum: Internal wall
Closed circulatory system
Well-developed nervous system
(brain + nerve cords)
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Hydrostatic Skeleton: A skeleton made up of fluid
under pressure in closed compartments.
Longitudinal
Muscle
Circular
Muscle
Longitudinal
Muscle
Circular
Muscle
• Contraction of longitudinal muscles- shorten
• Contraction of circular muscles- lengthen
• Alternate muscular contractions: longitudinal,
circular, longitudinal, circular, etc.
Worm Ranch: http://dsc.discovery.com/tvshows/dirty-jobs/videos/worm-rancher.htm
Eating a worm: http://dsc.discovery.com/tvshows/man-vs-wild/videos/whopper-worm.htm
• Sexual & Asexual
• Polychaets- Dioecious
• Oligochaetes & Hirudinia- Monecious
• Clitellum: leeches and earthworms
Class Polychaets do not use clitellum for
reproduction!
• Oligochaetes &
Hirudinia- Monecious
•Clitellum: leeches and earthworms
Class Polychaets do not use clitellum for reproduction!
• Habitat: Primarily
freshwater, few marine.
Abundant in tropical
regions.
• Size: Most between 2-6 cm
in length.
• Color: Variety of colors and
patterns: black, brown, red,
or olive green.
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Monecious.
After fertilization, clitellum secretes a mucous –like
cocoon that receives eggs & sperm.
Bury mucous cocoon in mud.
Development process is similar to Oligochaetes.
Medicinal uses: circulation, anti-clotting
(Produces anticoagulant that prevents blood
from clotting.)
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External parasite with suckers on each end.
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Habitat: mucous-lined burrows near low tide.
Most active at night.
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Size: Grows up to 30-40 cm in length.
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Diet: Particle feeders. Use cilia or mucus to
obtain food. Consume plankton.
Parapoda: Appendages of Polychaetes.
Function: Locomotion & breathing.
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