The Thin Cyclinella, Cyclinella tenuis (Récluz, 1852) is a local species from the family of Venus Clams, the Veneridae. The photo on the right of the illustration depicts a complete shell (paired valves) collected in March 2016 by shell museum volunteer Tom Annesley. That image shows the right valve (half-shell) on top and left valve on bottom. In the background, you can see the shell hinge, with its "teeth" and "sockets." The hinge, combined with the spring-like action of the ligament, ensures that the shell valves stay properly aligned during the repeated opening and closing motions of the shell by the mollusk. It also prevents the valves from sliding past each other during attempts from predators to separate them to reach (and eat) the animal inside.
The Thin Cyclinella, Cyclinella tenuis. Photos by José H. Leal.