The Bivalves (Class Bivalvia) include clams, oysters and scallops. They live in the ocean and in freshwater lakes and streams.
1) They have two flattened shells joined by a hinge, called the ligament.
2) The shells can open and close when needed, but are usually held closed by powerful muscles to protect them from predators.
3) Some can snap shut quickly to scoot away from predators.
4) Unlike many mollusks that feed using a rasping tongue, called a radula, bivalves feed by filtering food particles from the water.
5) They have a muscular “foot” with which they can attach themselves to rocks on the the ocean floor or dig in the sand.