Common Bivalve Dentition Patterns

Taxodont dentition is composed of numerous, small teeth perpendicular to the hinge axis. It is found mostly in ark shells (e.g., Arca, left) and nuculoids (nut shells).

Heterodont dentition consists of cardinal teeth (beneath the beak) and lateral teeth separated by a space with no teeth. Found in a wide variety of bivalves, particularly in burrowing clams.

Edentulous dentition has no hinge teeth, just a ligament area, as in this pearl oyster (Pteria).