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Annelida
The Segmented Worms
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Annelid Features
1. bilateral symmetry
2. coelom (coelomates)
3. segmented bodies
4. 2 body openings
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Class Polychaeta
the polychaetes
1. setae
2. parapodia
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polychaetes are hairy
parapodia with setae
a hair a setae
a foot a parapodia
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bristleworm
one type of polychaete
Polychaetes live in the ocean.
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close-up of parapodia
setae are not visible on ends of parapodia
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anterior end of a polychaete
mouth
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Class Oligochaeta
The Earthworms
1. setae
2. no parapodia
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Earthworms live in and eat soil they are
nocturnal (are active at night).
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Earthworms make good fishing bait.
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earthworms vary greatly in size
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External Structures
body segments
clitellum
mouth
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Circulatory System
dorsal blood vessel
ventral blood vessel
5 pairs of hearts
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represents the body
Earthworms have a closed circulatory system.
represents the heart
The dorsal blood vessel brings the blood back
from the body.
The ventral blood vessel pumps the blood to the
body.
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Excretory System
nephridia (one pair in each body segment)
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Nervous System
brain
ventral nerve cord
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Digestive System
anus
pharynx
mouth
esophagus
gizzard
intestine
crop
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Class Hirudinea
the leeches
1. no setae
2. no parapodia
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Examples of Leeches
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Leeches were once used in medicine, and still
are!!
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Leeches are blood-suckers
one sucker to suck blood
one sucker to attach to host
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Some are quite large!
eight inches
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The End