California Mussels have large, blue-black shells (also called valves) with irregular growth lines. The shells are thick and pointed at the end attached to the rocks. They broaden to an oval on the end exposed to the waves. The shells are blue-gray inside and somewhat iridescent. The animal is pale orange. California Mussels are firmly attached to the rocks and each other by byssal threads secreted by a gland at the base of the foot. Scientists are trying to synthesize the material that forms the threads to use as a marine adhesive.
Ochre Stars are the main predator. They’re also eaten by shorebirds, crabs and predatory snails. Humans have eaten California Mussels for thousands of years and they were introduced to the diet of European and American pioneers by the Native Americans living on the Oregon Coast. However, this delicacy can also be dangerous as the mussels may become poisonous in summer months when high concentrations of toxic plankton build up in their flesh.
These animals are found from the Aleutian Islands to southern Baja California.