Slender Cockle Shell, Mexicardia procera

Slender Cockle Shell, Mexicardia procera. Shell collected off the beach of Punta Chivato, Baja California Sur, June 2025. Size: 7.0 cm (2.8 inches) x 5.3 cm (2.1 inches) x 2.9 cm (1.1 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Slender Cockle Shell, Mexicardia procera. Shell collected off the beach of Punta Chivato, Baja California Sur, June 2025. Size: 8.0 cm (3.1 inches) x 6.2 cm (2.4 inches) x 3.0 cm (1.2 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Phylogeny: The Slender Cockle Shell, Mexicardia procera (G.B. Sowerby I, 1833), is a bivalve mollusk that is a member of the Cardiidae Family of Cockles and True Cockle Shells. The genus Mexicardia is one of forty-nine genera in this family, and this is the only species in this genus. They are also known as the Mexican Cockle Shell and in Mexico as Almeja Piconudo.

Description: Slender Cockle Shells are equivalve, inflated and tear-drop shaped profile. They are higher than they are long.  The exterior is sculpted with 21 to 24 heavy radial ribs. Small specimens have weak crossbars on the ribs. The outside color is white, with some having brown mottling or specks. The shell is usually covered with a thin tan periostracum. The inside is white with brownish purple shading toward the anterior. Slender Cockle Shells reach a maximum of 11.7 cm (4.6 inches) in height and 10.2 cm (4.0 inches) in length.

Habitat and Distribution: Slender Cockles are found on and within sand and mud substrates, from the intertidal zone to depths up to 26 m (85 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 Scammon’s Lagoon, Baja California, along the central and northwest coasts of the Baja Peninsula.

Ecology and Behavior: Slender Cockles are suspension feeders that feed primarily on plankton and other suspended organic matter. In turn they are preyed upon by crabs, fish, gastropods and sea stars. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization. Their engagement in any type of commensal, parasitic, or symbiotic relationships has not been formally documented. 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: Cardium dulcinea, Cardium ferruginosum, Cardium laticostatum, Cardium panamense, Cardium parvulum, Cardiuim procerum, Cardium rotundatum, Laevicardium (Mexicardia) procerum, Trachycardium (Mexicardia) panamense, Trachycardium (Mexicardia) procerum, Trachycardium panamense, Trachycardium procerum, and Trachycardium eudoxia.