Coral Hinged Chama Shell, Chama coralloides

Coral Hinged Chama Shell, Chama coralloides. Size: 8.1 cm (3.2 inches) x 5.7 cm (2.2 inches). Shell collected in the along the coast of Bahía Concepción, Baja California Sur, March 2005. Collection, photograph and identification courtesy of Bob Hillis, Ivins, Utah.

Phylogeny: The Coral Hinged Chama Shell, Chama coralloides (Reeve, 1846), is a member of the Chamidae Family of Jewel Box Shells.   The genus Chama is one of six genera in this family, and there are thirty-nine species in this genus. They are also known as the Violet Oyster Shell.

Description: The Coral Hinged Chama Shell has an ovate profile and has the ability to modify its shape to match the surface to which it is attached. The shell is thick, and either the right or left valve may be cemented to the substrate. The exterior is spiny, though in larger specimens the spines are often eroded or overgrown. The exterior of the shell is gray to cream in color. The interior has a coral red hinge surrounded with deep purple and/or pink. The Coral Hinged Chama Shell reaches a maximum of 11.6 cm (4.5 inches) in length and 6.0 cm (2.4 inches) in height.

Habitat and Distribution:  The Coral Hinged Chama are found on rock and other hard surfaces. They live in the intertidal zone and to depths up to 25 m (80 feet). They are a subtropical to tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean with the exception that they are absent from north of Magdalena Bay, Baja California Sur along the central and northwest coasts of the Baja Peninsula and north of Bahía de los Ángeles, Baja California in the Sea of Cortez.

Ecology and Behavior:  Coral Hinged Chama Shells are suspension feeders  that feed primarily on planktonic algae. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization.  There is no mention in the available literature of them engaging in any types of parasitic, commensal, or symbiotic relationships. They are harvested as food in artisanal fisheries. From a conservation perspective they have not been formally evaluated however they are fairly common with a relatively wide distribution and should be consider to be of Least Concern.

Synonyms: Chama frondosa var. mexicana.