The name "bivalve" refers to
the two-part shell that characterizes these mollusc species. The two
valves of the shell are joined by a ligamentous hinge and held shut
by a pair of strong adductor muscles.
Bivalves are exclusively aquatic; they include both marine and freshwater
forms. Includes marine clams, oysters, mussels and scallops and freshwater
mussels and they can be sessile or sedentary.
Bivalves are filter-feeders which extract organic matter from the water
in which they live.
Around 20,000 known species.
The shells made of calcium carbonate can display different forms
Shells of bivalves
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