Many-ridged Venus Clam Shell, Periglypta multicostata

Many-ridged Venus Clam Shell, Periglypta multicostata. Shell provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, February 2017. Size: 13 cm (5.1 inches) x 11 cm (4.3 inches).Identification courtesy of Bob Hillis, Ivins, Utah.

Many-ridged Venus Clam Shell, Periglypta multicostata. Shell collected off the beach at Punta Chivato, Baja California Sur, February 2022. Size: 9.5 cm (3.7 inches) x 8.2 cm (3.2 inches). Photograph and Identifications courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

Phylogeny: The Many-ridged Venus Clams, Periglypta multicostata (G. B. Sowerby I, 1833), is a bivalve mollusk that is a member of the Veneridae Family of Venus Clam Shells. The genus Periglypta is one of one hundred seven genera in this family, and there are eight species in this genus. They are known in Mexico as Almeja Acanalada and Almeja Costillada.

Description: Many-ridged Venus Clams are large, heavy, and have an oval outline. The posterior end is longer and more rounded than the anterior end. They have prominent cardinal teeth and the external surface is sculpted with numerous, closely-space concentric ridges, crossed by fine radiating lines. The exterior of the shell is cream colored, with tan or light brown concentric markings. The interior is cream colored. Many-ridged Venus Shells reach a maximum of 13.7 cm (5.4 inches) in length and 11.8 cm (4.7 inches) in height.

Habitat and Distribution: Many-ridged Venus Clams are found in sand substrate, often under rocks within the intertidal zone to epths up to 15 m (50 feet). They are a subtropical to tropical Eastern Pacific species that are found in Mexican waters of the Pacific Ocean from Santa Rosalia, Baja California Sur south to Guatemala. They have not been documented along the west coast of the Baja Peninsula.

Ecology and Behavior:  Many-ridged Venus Clams 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:  Antigona multicosta, Venus multicostata, and Venus thouarsii.