Mollusks

Knobbed Whelk
Knobbed Whelk (Busycon carica)

NPS photo

For many beach-goers to Assateague Island, shell collecting is a popular activity. When searching for that perfectly intact beautifully colored shell, take a moment to think about the animals called mollusks that created and lived in these treasures. Mollusks create their shell as they grow. They do this with a part of their body called the mantle, along with calcium deposits. Bivalves, like clams build shell along the edges and thicken it from within. Snails such as whelks grow in an increasing spiral, moving their body attachment as they grow.

Gastropods are subclass of mollusks that most people refer to as snails. The knobbed whelk (Busycon carica), and channeled whelk (Busycon canaliculatum) are often mistaken for their southern cousins the conch, however these whelks are found in more northern territories and feed on bivalves.

 
Quahog Clam
Quahog Clam (Mercenaria mercenaria)

NPS photo

Bivalves are creatures that are encased by two shells attached by a hinge. Bivalves such as the quahog clam (Mercenaria mercenaria), oyster (Crassostrea virginica), and ribbed mussel (Geukensia demissa) support a large commercial industry and livelihood for the people living near Assateague Island. They are also filter feeders aiding in keeping our waters clean.
 
View of a squid head and eye
Brief squid (Lolliguncula brevisare)

NPS photo

Not all mollusks are comprised of shells we desperately desire to collect. Brief squid (Lolliguncula brevisare) is a type of mollusk that has an internal shell which supports its soft body. Called a pen, this shell is transparent and resembles plastic, which may contribute to the reason sea creatures get confused and attempt to eat plastic debris in the ocean. When threatened, a squid will propel itself backwards and may possibly release ink.

Shell collecting on Assateague Island is allowed, and is limited to one gallon of empty shells per person. Stop by our visitor centers and pick up a shell identification brochure.

Last updated: July 28, 2018

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