Shell of the Week: The Digitate Thorny Oyster
Reaching about 70 mm in size, Spondylus tenuis Schreibers, 1793, is one of the few species of thorny oysters (family Spondylidae) found in the western Atlantic. Its shell comes in varied colors, including rusty brown, brick red, orange, cream-yellow, whitish, or variations of these hues. The sculpture consists of flat or pointy spines that are longer toward the edge of the shell. The lower valve is almost always cemented to a hard surface, such as rocks, ship wrecks, or oil platforms, but sometimes the larva may attach to a small piece of shell or coral fragment, causing that individual to live a free, unattached existence through adulthood. That is the case of this small but complete shell, collected by Ginger MacKeen on Honeymoon Island in June 2019. Notice the sturdy hinge in this species.