bivalve

/ˌbaɪˈvælv/

Other forms: bivalves

A bivalve is a sea creature with two shells, one on top and one underneath, connected by a kind of hinge. Mussels and clams are bivalves; snails and abalone are not.

Bivalves are soft on the inside with a very hard, protective shell on the outside. You know you're looking at a bivalve when you see two distinct halves of that shell, which can swing shut like a door when the animal perceives danger. Oysters fall into this category, and so do scallops. Bivalve, literally "two valves," comes from the Latin valva, "section of a folding door."

Definitions of bivalve

1. noun

   marine or freshwater mollusk having a soft body with platelike gills enclosed within two shells hinged together
   synonyms: lamellibranch, pelecypod

   types:

   clam

   burrowing marine mollusk living on sand or mud; the shell closes with viselike firmness

   cockle

   common edible, burrowing European bivalve mollusk that has a strong, rounded shell with radiating ribs

   oyster

   marine mollusks having a rough irregular shell; found on the sea bed mostly in coastal waters

   ark shell

   marine bivalve mollusk having a heavy toothed shell with a deep boat-like inner surface

   blood clam

   red-blooded clam

   mussel

   marine or freshwater bivalve mollusk that lives attached to rocks etc.

   escallop, scallop, scollop

   edible marine bivalve having a fluted fan-shaped shell that swim by expelling water from the shell in a series of snapping motions

   piddock

   marine bivalve that bores into rock or clay or wood by means of saw-like shells

   Mya arenaria, long-neck clam, soft-shell clam, steamer, steamer clam

   an edible clam with thin oval-shaped shell found in coastal regions of the United States and Europe

   Mercenaria mercenaria, Venus mercenaria, hard clam, hard-shell clam, quahaug, quahog, round clam

   an edible American clam; the heavy shells were used as money by some American Indians

   geoduck

   a large edible clam found burrowing deeply in sandy mud along the Pacific coast of North America; weighs up to six pounds; has siphons that can extend to several feet and cannot be withdrawn into the shell

   jackknife clam, knife-handle, razor clam

   marine clam having a long narrow curved thin shell

   Tridacna gigas, giant clam

   a large clam inhabiting reefs in the southern Pacific and weighing up to 500 pounds

   Cardium edule, edible cockle

   common edible European cockle

   seed oyster

   a young oyster especially of a size for transplantation

   blue point, bluepoint

   small edible oyster typically from the southern shore of Long Island

   Japanese oyster, Ostrea gigas

   a large oyster native to Japan and introduced along the Pacific coast of the United States; a candidate for introduction in Chesapeake Bay

   Virginia oyster

   common edible oyster of Atlantic coast of North America

   Pinctada margaritifera, pearl oyster

   tropical marine bivalve found chiefly off eastern Asia and Pacific coast of North America and Central America; a major source of pearls

   Anomia ephippium, saddle oyster

   thin-shelled bivalve having the right valve deeply notched

   Placuna placenta, capiz, window oyster, windowpane oyster

   marine bivalve common in Philippine coastal waters characterized by a large thin flat translucent shell

   marine mussel, mytilid

   marine bivalve mollusk having a dark elongated shell; live attached to solid objects especially in intertidal zones

   freshwater clam, freshwater mussel

   bivalve mollusk abundant in rivers of central United States

   Pecten irradians, bay scallop

   a small scallop inhabiting shallow waters and mud flats of the Atlantic coast of North America

   Pecten magellanicus, giant scallop, sea scallop

   a large scallop inhabiting deep waters of the Atlantic coast of North America

   shipworm, teredinid

   wormlike marine bivalve that bores into wooden piers and ships by means of drill-like shells

   type of:

   mollusc, mollusk, shellfish

   invertebrate having a soft unsegmented body usually enclosed in a shell
2. adjective

   used of mollusks having two shells (as clams etc.)
   synonyms: bivalved

   lamellibranch, pelecypod, pelecypodous

   bivalve

   antonyms:

   univalve

   used of mollusks, especially gastropods, as snails etc.

   single-shelled

   univalve