Cepoides Ark Shell, Anadara cepoides

Cepoides Ark Shell, Anadara cepoides. Size: 7.6 cm (3.0 inches) x 6.9 cm (2.7 inches). Shell collected off the beach at Km 26, Cero Colorado, Baja California Sur, March 2010. Identification courtesy of Bob Hillis, Ivins, Utah.

The Cepoides Ark, Anadara cepoides (Reeve, 1844), is a bivalve mollusk that is a member of the Arcidae Family of Arks. The shell is a sturdy with an almost oval outline, with a broadly rounded anterior end and a chopped-off posterior end. The shells are inflated with a prominent beak. The exterior of the shell is sculpted with 30 to 35 radial ribs and the interior margin of the shell is deeply grooved. The exterior is white in color and covered with a thin brown periostracum; the interior is white. The Cepoides Ark Shells reach a maximum of 9.0 cm (3.5 inches) in length and 8.2 cm (3.2 inches) in height.

Cepoides Arks are found within sand substrate at depths between 10 m (35 feet) and 84 m (275 feet). In Mexican waters they are found in the Sea of Cortez from Gonzaga Bay, Baja California to Cabo San Lucas, Baja California Sur and they range south to Ecuador. They have not been documented from the West Coast of the Baja Peninsula.

A synonym is Arca cepoides.