Solid Ark Shell, Arcopsis solida

Ark Shells of the Noetiidae Family are very similar in appearance to the Ark Shells of the Arcidae Family. They are ribbed clam shells with both valves being symmetrical and are trapezoidal or oblong in shape. Shells in this family are usually white or cream colored with a heavy, brown, periostracum (outer membrane) covering the shell’s surface. Noetiidae Shells differ from Arcidae Shells in the placement of ligaments and presence of striations on the ligaments. Species in this family are suspension feeders, filtering plankton and fine detritus from the surrounding water. These shells are preyed on by sea stars and carnivorous mollusks. Noetiidae Ark Shells are found in tropical and semi-tropical waters around the world, from the intertidal zone to moderately deep water. The family has thirty-eight global species, three of which are found along the coastlines of the Baja Peninsula.