1. WARM UP
Compare and contrast the three main classes of mollusks (Cephalopoda, Gastropoda, and Bivalvia) in terms of their body structure.

2. Segmented Worms
Phylum Annelida

3. General Characteristics
Annelida means “little rings”
15,000 species
Live in soil, fresh water, salt water

4. Structure Body divided into segments Organ Systems Powerful movement
Segments have muscles and setae (hairs)
Potential specialization
Organ Systems
Digestive
Circulatory
5 pairs of “hearts” and blood vessels
Nervous
Ganglia and nerve cord

5. Reproduction Hermaphroditic Cocoon over clitellum
Two earthworms exchange sperm
Cocoon over clitellum
Slides to pick up eggs and then sperm
Slides off worm

6. Diversity Earthworms Class Oligochaeta “few bristles”
Eat soil to get bits of organic matter
Exchange gases from water directly through the skin
Basic responses to light, temperature, moisture

7. Diversity Marine Worms Class Polychaeta “many bristles”
Largest group of annelids
Setae are large, and in bundles
Attached to parapodia
The first “legs”

8. Diversity Leeches Class Hirudinae Don’t have setae Aquatic
A few feed on blood
Attach with suckers
Produce chemicals so you can’t feel them
Used in surgery to keep blood flowing

9. WRAP UP
Make a triple Venn diagram to compare and contrast the three classes of annelids.