1. Lecture 5 Animal Evolution – The Invertebrates

2. Gastropods:  largest of class, most diverse  include snails & slugs.  foot spreads while crawling.  many species spirally coiled/conical shells. Chitons:  slow-moving/sedentary grazers.

3. Bivalves: –two-valved shell. –include clams, scallops, oysters & mussels. Cephalopods –highly active predators of the sea. –include swiftest (squid), largest invertebrates (giant squid) & the smartest (octopuses). –have some memory power & capacity to learn thus most complex invertebrates.