why are mussels and clams called bivalves
The generally accepted systematic name (in contrary to some others) of all mussels, clams and scallops-Bivalvia-the two-valve molluscs-refers to the most important character of all bivalves, that separates them from all other molluscs: The shell is separated into two pieces. bivalve's foot is adapted to how it lives and moves. So there are different types of feet in bivalves, from beam-shaped, tongue-shaped or worm-shaped feet. Swimming mussels, as well as completely sessile mussels, often have a largely reduced foot.