The name bivalve indicates that the main feature of this class of molluscs have two shells. Bivalves include mussels, scallops, cockles, oysters, clams and the unusual shipworms.
Bivalves are two shelled aquatic molluscs, bilaterally symmetrical and laterally compressed.
The mantle cavity contains a respiratory chamber and the food gathering mechanism. The mantle cavity also discharges waste and reproductive products, The mantle itself secretes the shell. Most bivalves have a well-developed foot that is used for burrowing and creeping. Other fixed bivalves, such as the oysters , have lost the use of the foot completely. Most bivalves are sedentary and may live either in or on the substrate.