Harold McGee

Bivalve Adductor Muscles

Appears in
On Food and Cooking
On Food and Cooking

By Harold McGee

Published 2004

  • About
The two-shelled or “bivalve” molluscs must spread their shells apart to allow water and food particles in, and pull their shells together to protect their soft innards against predators or—in the case of intertidal mussels and oysters—the drying air. To do this work they have evolved a special muscle system, one that poses some challenges to the cook but is mostly a boon, since these prepackaged animals can survive for many days in the refrigerator covered only with a moist towel.

Bivalve shells are normally held open mechanically, by means of a spring-like ligament that connects and pulls them together at the hinge end, and thus pulls the opposite wide ends apart. To close the shells, the animal must power a muscle, called an “adductor” (from the Latin adducere, “to bring together”), which extends between the broad ends of the shell and contracts to overcome the spring force of the ligament.