What Perch on Branches, Have Wings But Do Not Fly?
As the image shows, this branching colony of a Regal Sea Fan, Leptogorgia hebes, was host to at least eleven Atlantic Wing Oysters, Pteria colymbus. Wing oysters get their common name from the wing-like expansions on their shells, also known as "auricles". Atlantic Wing Oysters are commonly found living in association with sea fans, sea whips, and other gorgonians, attaching to them via byssal threads.
The byssal threads of Atlantic Wing Oysters wrap strongly around the stems and branches of sea fans, in some cases causing the coenenchyme (the outer layer that surrounds the polyps of a sea fan) to fall away exposing the colony skeleton to fouling by other organisms. Atlantic Wing Oysters may grow to about 6.9 cm (about 2.75 inches), and are brownish, with rays of lighter color. The shells of young individuals show relatively larger auricles than those of adult shells. Wing oysters and pearl oysters are members of the family Pteriidae and, as such, are not closely related to true (edible) oysters. This interesting grouping of sea fan and mollusks was recently collected by Amy Tripp on Kice Island, Florida.