Tough Softies!

 Kingdom: Animalia ◦ Phylum: Mollusca (Mollusks)  Class: Bivalvia (Bivalves)  Class: Cephalopoda (Cephalopods)  Class: Gastroboda (Gastropods) Mollusca is the second most diverse (second most number of species) phylum in the animal kingdom!

 soft-bodied  bilateral symmetry  coelomates ◦ allows for some organ movement ◦ allows for organ filling and emptying  most have a shell  3 part body plan ◦ visceral mass ◦ mantle ◦ foot

 have radula (except bivalves) ◦ tongue-like organ covered with teeth  nephridia ◦ tubular structure to filter sugars, salts to keep and toxins to expel  three chambered heart  open circulatory system (except octopuses)

 most breathe with gills ◦ located in mantle cavity ◦ extract 50% of dissolved oxygen ◦ terrestrial snails have primitive lungs that must stay moist ◦ some sea snails breathe through skin  most have separate sexes ◦ some snails and slugs are hermaphrodites ◦ some slugs and oysters can change sex ◦ trochophore larva

 “stomach-feet”  snails and slugs  terrestrial, freshwater, or terrestrial  most have tentacles with eyes on head  most have one shell ◦ slugs and nudibranches have none  slide on mucus or fly through water  use their radula in many different ways ◦ herbivores or predators ◦ nudibranches can capture and use nematocysts to hunt

 “head-feet”  Octopus, squid, cuttlefish, nautilus  tentacles ◦ 8-90 ◦ suction cups or hooks  lack shell ◦ nautilus has a shell ◦ squid and cuttlefish has internal shell  well-developed brain  jet propulsion ◦ draw water into mantle cavity and expel it through siphon  squid and octopuses can release “ink”

 “two-doors”  muscles, oysters, clams, scallops  nacre – mother-of- pearl coating in shells  no distinct head, no radula  most are sessile ◦ scallops move  filter-feed ◦ particles moved along gills to mucus-covered groove into mouth