What is the difference between Molluscs and crustaceans. Is it that crustaceans have shells and molluscs dont because I thought barnacles were molluscs but they have shells.
Other information on classification would also be handy thanks
Just to clear up RATTER15's misconception first. A tortoise has an internal skeleton and is a vertebrate. It is a reptile.
Molluscs have an unsegmented body and a mantle that often secretes a shell. eg snail, slug, oyster, squid
Crustaceans have segmented bodies, an exoskeleton, and jointed limbs. Crustaceans have to shes their exoskeleton in order to grow. eg woodlouse, crab, krill, barnacle