Home > Invertebrates > Bivalves > Calloarca tenella

Updated 8/20/2025

Family Arcidae

INDO-PACIFIC / HAWAII

Calloarca tenella

Kaupo, Oahu, 10 feet

 

SMOOTH ARK

Common under dead coral at any depth, attached with the hinge facing outward.  The lightweight shell has fine radiating ribs and coated with a thin brown periostracum.  Attains 1.2 inches, 30 mm.  Red Sea to Hawaii and the Tuamotus.  Formerly known as Barbatia tenella.