Mexican Jewel Box Shell, Charma buddiana

Mexican Jewel Box Shell, Charma buddiana. Shell collected off the beach of Punta Chivato, Baja California Sur, July 2023. Size: 7.6 cm (3.0 inches) x 6.4 cm (2.5 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Phylogeny: The Mexican Jewel Box, Chama buddiana (C.B. Adams, 1852), is a bivalve mollusk that 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 forty-two species in this genus.  In Mexico this species is known as Almeja Joyero de Mexicano.

Description: The Mexican Jewel Box shell is chunky and irregular in shape. The exterior surface is covered with short, irregular spines. The margin is finely crenate. The shell has a dark red exterior with small and large white spines set in irregular rows. The shell has a red outer margin. The interior of the shell is white with a pink band near the margin.  Mexican Jewel Box Shells reach a maximum of 12.5 cm (4.9 inches) in length and 10.5 cm (4.1 inches) in height. The Mexican Jewel Box is very similar to the Coral Hinged Chama Shell, Chama coaralloides, which lacks the pink band near the margin.

Habitat and Distribution: Mexican Jewel Boxes attach themselves to rocks and coral, via their left valve within the intertidal zone to depths up to 90 m (295 feet). They are a subtropical to tropical Eastern Pacific species that are found in Mexican waters of the Pacific Ocean along the coast of the mainland from Mazatlán, Jalisco Bahía de Choya, Sonora south to Guatemala. In the Sea of Cortez they are found south of Bahía de Choya, Sonora. They are absent from along the west coast of the Baja Peninsula.

Ecology and Behavior:  Mexican Jewel Boxes are suspension feeders that feed primarily on planktonic algae and suspended organic matter. 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. From a conservation perspective they have not been formally evaluated however they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.

Synonyms: Chama frondosa var. fornicata