The Assateague



The Atlantic Slipper Shell (Crepidula fornicata)
up to about 1.5 inches

Two kinds of slipper shells are common along the Atlantic coast, the Atlantic and the Eastern white slipper shell. The Eastern white slipper shell (Crepidula plana) is white and flattened, sometimes a little convex or concave, while the Atlantic slipper shell (photos) is arched with brown markings and an apex that is bent downward to one side at the back.

Both will attach themselves to a hard object in the water and spend their lives in that one place filtering food. The upper photo shows a number of slipper shells that have attached themselves to the rear underside of a horseshoe crab. You'll also find them attached to other shells along the beach, such as whelks, or to each other in stacks. While all start as males, those that begin a stack change to female while those on top will most often be male--unless there is a shortage of females.

Unlike a bivalve (two-part shell) such as the clam or oyster, the slippers have a one-part shell with the creature's foot on the underside along with a shelf (lower right photo) that extends about half the length of the shell in the case of the Atlantic slipper (less than half for the Eastern white). Slippers received their names because of the resemblance to household slippers.

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