answersLogoWhite

0

These are called valves- some molluscs have two and are called BIVALVES, whilst others have three and are called TRIVALVES. The latter are held to be higher up the evolutionary scale. The bivalves are the clams, mussels, oysters and scallops. The adults all have two hinged shells (valves). Some of these animals circulate water carrying the microorganisms that they eat and oxygen for respiration through tubes called "siphons" that they can extend from between the shells on the anterior end so they can stay safely hidden in the mud or sand.

User Avatar

Wiki User

16y ago

What else can I help you with?