San Diego Scallop Shell, Leopecten diegensis

San Diego Scallop Shell, Left Valve, Leopecten diegensis.

San Diego Scallop Shell, Right Valve, Leopecten diegensis.  Size: 12.2 cm (4.8 inches) x  10.3 cm (4.1 inches). Shell collected from the beach in the greater San Diego area, San Diego, California. Collection, photograph and identification courtesy of Bob Hillis, Ivins, Utah.

Phylogeny: The San Diego Scallop Shell, Leopecten diegensis (Dall, 1898), is a bivalve mollusk that is a member of the Pectinidae Family of Scallop Shells. The genus Leopecten is one of sixty-four genera in this family, and there are five species in this genus. They are known in Mexico as Vieira de San Diego.

Description: The San Diego Scallop Shell is a classic fan-shaped scallop with equal sized auricles (ears) on both sides of the hinge. The right valve is somewhat convex with radiating flat-topped ribs. The left valve is flat or slightly convex with rounded ribs. The two valves are differently colored, the right valve is buff, orange, white or yellow and the left is brown or reddish brown, sometimes with white specks or blotches. San Diego Scallops reach a maximum 12.7 cm (5.0 inches) in length and 10.7 cm (4.2 inches) in height.

Habitat and Distribution: San Diego Scallops are found on shale or sand bottoms at depths between 10 m (30 feet) and 400 m (1,300 feet). They are a subtropical to tropical Eastern Pacific species that have a limited range in Mexican waters of the Pacific Ocean being found only along the west coast of the Baja Peninsula.

Ecology and Behavior: San Diego Scallops are suspension feeders that feed primarily on plankton and suspended organic matter. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization.  Their engagement in any type of commensal, parasitic, or symbiotic relationship has not been formally documented. From a conservation perspective the San Diego Scallop has not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.

Synonyms: Euvola diegensis, Flabellipecten diegensis, Pecten (Pecten) diegensis, Pecten diegensis, and Pecten floridus.