mollusk, or mollusc, Any of some 75,000 species of soft-bodied invertebrate animals (phylum Mollusca), many of which are wholly or partly enclosed in a calcium carbonate shell secreted by the mantle, a soft covering formed from the body wall. Between the mantle and the body is the mantle cavity. Mollusks occur in most habitats from the deep sea to high mountains. Living mollusks are usually grouped into eight classes: Gastropoda (see gastropod), Bivalvia or Pelecypoda (see bivalve), Cephalopoda (see cephalopod), Scaphopoda (tusk shells), Aplacophora (Solenogasters), Caudofoveata (sometimes included in the Aplacophora order), Polyplacophora (chitons), and Monoplacophora. Mollusks are economically important as food, and their shells are widely used in jewelry and decorative items.
mollusk Article
mollusk summary
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies.
Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Learn about the classification and economic importance of mollusks
Below is the article summary. For the full article, see mollusk.
oyster Summary
Oyster, any member of the families Ostreidae (true oysters) or Aviculidae (pearl oysters), bivalve mollusks found in temperate and warm coastal waters of all oceans. Bivalves known as thorny oysters (Spondylus) and saddle oysters (Anomia) are sometimes included in the group. True oysters have been
clam Summary
Clam, in general, any member of the invertebrate class Bivalvia—mollusks with a bivalved shell (i.e., one with two separate sections). More than 15,000 living species of bivalves are known, of which about 500 live in fresh water; the others occur in all seas. Bivalves usually live on or in sandy or
cephalopod Summary
Cephalopod, any member of the class Cephalopoda of the phylum Mollusca, a small group of highly advanced and organized, exclusively marine animals. The octopus, squid, cuttlefish, and chambered nautilus are familiar representatives. The extinct forms outnumber the living, the class having attained
bivalve Summary
Bivalve, (class Bivalvia), any of more than 15,000 species of clams, oysters, mussels, scallops, and other members of the phylum Mollusca characterized by a shell that is divided from front to back into left and right valves. The valves are connected to one another at a hinge. Primitive bivalves