Pacific Fly-speckled Cerith Shell

Pacific Fly-speckled Cerith Shell, Cerithium sterimuscarum. Shell collected off a beach in the greater Los Cabos area, Baja California Sur, May 2005. Size: 3.0 cm (1.2 inches) x 1.5 cm (0.6 inches). Identification courtesy of Bob Hillis, Ivins, Utah.

The Pacific Fly-speckled Cerith, Cerithium stercusmuscarum (Valenciennes, 1833, is a gastropod mollusk that is a member of the Cerithiidae Family of Ceriths. The shell is stout  and solidly built that consist of six to eight whorls with a row of pointed knobs separate the whorls. These knobs are more noticeable in some specimens than others. The oval-shaped aperture and the siphon canal are fairly small. The exterior color of the shell may be blue-gray, charcoal, or brown, with fine white speckles; the apex is often white; the interior is white or bluish; the rim of the outer lip is often darker colored; and the bottom of the inside edge of the aperture (columella) is often white. The Pacific Fly-speckled Cerith Shell reach a maximum height of 3.5 cm (1.4 inches) and 1.7 cm (0.7 inches) in height.

The Pacific Fly-speckled Cerith are found on sand flats and within sand and mud substrate inside estuaries in the intertidal zone to depths up to 6 m (20 feet). They range from Magdalena Bay, Baja California Sur to Peru, including the Galapagos Islands, and are found throughout the Sea of Cortez.