A marine or freshwater invertebrate belonging to the Class Bivalvia in the Phylum Mollusca. Bivalves are generally called “clams,” but they also include scallops, mussels, cockles, and oysters. Bivalves are characterized by right and left shells. Each half of these hinged shells is called a valve. Bivalves are filter feeders, collecting food particles from the water with their gills.