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

Segmented Worms Phylum Annelida

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

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

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

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

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

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

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