why are they called bivalves

They are called "bivalves" because their shells consist of two hinged parts or "valves." The name comes from the Latin words "bis," meaning two, and "valvae," meaning leaves of a door or shell halves. This two-part shell structure allows the shell to open and close, protecting the soft-bodied animal inside. The taxonomic term "Bivalvia" was first used by Linnaeus in 1758 specifically to describe animals with shells made of two valves joined by a hinge.