Bivalves

Bivalvia, commonly referred to as bivalves, are the class of marine and freshwater mollusks with laterally compressed bodies enclosed by a shell in two hinged parts. They include clams, oysters, mussels, scallops, and numerous other families. The majority are filter feeders and have no head or radula. The gills have evolved into ctenidia, specialized organs for feeding and breathing. Most bivalves bury themselves in sediment on the seabed, where they are safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. A few bore into wood, clay or stone and live inside these substances. Some bivalves, such as the scallops, can swim.