Lurid Ark Shell, Barbatia lurida

Lurid Ark Shell, Barbatia lurida. Shell collected from the beach at Punta Chivato, Baja California Sur, December 2022.  Size: 3.0 cm (1.2 inches) x 1.8 cm (0.7 inches) x 0.6 cm (0.2  inches). Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

Lurid Ark Shell, Barbatia lurida. Shell collected from the beach at Punta Chivato, Baja California Sur, December 2022.  Size: 6.2 cm (2.4 inches) x 3.7 cm (1.5 inches) x 1.2 cm (0.5  inches). Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

The Lurid Ark, Barbatia lurida (G.B. Sowerby I, 1833), is a bivalve mollusk that is a member of the Arcidae Family of Arks. They obtain their name from their shell that has alternating teeth along the hinge that allow the shell to close securely. The shell has an ovate shape with a rounded anterior and a wider and sloped posterior end. The beak is wide and low. There are fine, radiating lines across most of the shell. The anterior of the shell is tan in color. The posterior is dark brown to purplish in color. According to some sources Lurid Ark Shells reach a maximum length of 5.1 cm (2.0 inches) in length, although Dr. Colin Campbell has found specimens that are 6.2 cm (2.4 inches) in length, and 3.7 cm (1.4 inches) in height.

Lurid Arks attach themselves to rocks with fine silky byssus, giving rise to their genus name – Barbatia (bearded one). This species lives intertidally, and to a depth of 30 m (100 feet). It ranges from the northern end of the Sea of Cortez to Peru.

Synonyms include  Byssoarca lurida and Byssoarca vespertilio.