Two-banded Moon Shell, Polinices bifasciatus

Two-banded Moon Shell, Polinices bifasciatus. Shell collected off the beach of Punta Chivato, Baja California Sur, May 2023. Size:  3.8 cm (1.5 inches) x 3.1 cm (1.2 inches). Collection, identification and photographs courtesy of Colin Campbell, DVM, Punta Chivato.

Two-banded Moon Shell, Polinices bifasciatus. Shell collected off the beach of Punta Chivato, Baja California Sur, May 2023. Size:  4.0 cm (1.6 inches) x 3.0 cm (1.2 inches). Collection, identification and photographs courtesy of Colin Campbell, DVM, Punta Chivato.

Two-banded Moon Shell, Polinices bifasciatus. Size: 5.1 cm (2.0 inches) x 3.9 cm (1.5 inches). Shell collected in the along the coast of Bahía Concepción, Baja California Sur, March 2015. Collection, photograph and identification courtesy of Bob Hillis, Ivins, Utah.

The Two-banded Moon, Polinices bifasciatus (Gray in Griffith and Pidgeon, 1833), is gastropod mollusk that is a member of the Naticiae Family of Moons. They are shells of about four whorls with a low spire and a fairly pointed apex. They have a large semi-circular aperture. The exterior of the shell is smooth and light-brown in color, with two, narrow, but widely separated, white bands. The area adjacent to the inner edge of the aperture is dark brown. The interior is white. The Two-banded Moon Shells reach a maximum of 5.6 cm (2.2 inches) in length and 4.3 cm (1.7 inches) in height.

Two-banded Moons are found on and within mud and sand substrate in the intertidal zone to depths up to 3 m (10 feet). They range from the northern Sea of Cortez to Panama; they have not been not documented as residents of the West Coast of Baja.

A synonym is Natica bifasciatusis.