 The name "bivalve" is derived from the Latin bis, meaning "two", and valvae, meaning "leaves of a door". Not all animals with shells with two hinged parts are classified under Bivalvia; other animals with paired valves include certain gastropods (small sea snails in the family Juliidae), members of the phylum Brachiopoda and the minute crustaceans known as ostracods and conchostrachans.
