Mollusk structure
Bilateral symmetry; often distinct head; muscular foot for locomotion
Visceral mass: digestive, excretory, and reproductive organs
Mantle: folds of dorsal tissue, enclose a cavity between dorsal body wall and visceral mass - mantle cavity (not to be confused with coelom!)
Outer protective shell (1 in snails, 2 in clams)
Gills or lung: in mantle cavity
Open blood system /w heart
Coelom is small cavity around the heart
Nephridia: excretory organs; ciliate funnel open to coelom, collects nitrogenous waste and channels it to mantle cavity