Amber Pen Shell
Pinna carnea Gmelin, 1791
Family Pinnidae (Pen Shells or Fan Shells)
Pinna carnea is known as the Razor Shell in the Bahamas, reflecting its typical in situ posture with its fragile yet sharp posterior edges protruding from the sand. If dislodged slightly, pen shells can rebury by expelling water from the buried part of the shell, effectively “fluidizing” the sand to bury deeper. If dislodged completely, though, it cannot rebury. Predators include starfish and carnivorous snails. The shells often support a community of attached organisms, including algae, sponges, and polychaete worms. Commensal pea crabs and shrimps often live in the mantle cavity of the living pen shell.