mollusc bivalve *Bivalvia*, in previous centuries referred to as the *Lamellibranchiata* and *Pelecypoda*, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. Bivalves as a group have no head and they lack some usual molluscan organs like the radula and the odontophore. They include the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater.[https://en.wikipedia.org/wiki/Bivalvia] bivalvia lamellibranchiata pelecypod pelecypoda requires discussion