Mollusk Features Complete digestive system Bilateral symmetry Move on muscular foot 3 part body plan –A) Radula tongue-like organ to scrape food –B) Mantle Covers internal organs secretes shell –C) Ctenidia Gills to extract oxygen

Mollusk Features Have organ systems Usually separate male/female sexes –Methods vary –Snail “love- darts” Shells –made of protein and calcium –Some internal

Gastropods: slugs, snails “Stomach Foot” Mostly marine Most single shell Foot secretes slime to move Feeding: –Herbivores: scrape food with radula –Predators: poisonous dart to swallow prey whole

Cone snail eats fish

Bivalves: clams Most marine Shell secreted by mantle No distinct head region or radula –Filter feeders Sperm & egg released into water –Larvae free swimming

Cephalopods: squid, octopus “Head foot” –L–Large head attached to tentacles Complex nervous system & brain Expel water through siphon to move –J–Jet propulsion Active predators

The Cuttlefish

The Cuttlefish in Action