These mollusks are named bivalves for their paired shells. The two halves are joined at one edge by a flexible hinge that when closed against the other half, forms a domed space near the hinge of the shell which accommodates the bulk of the mollusk’s body and narrows towards the edge of the shell that opens.
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- Oysters thrive in the brackish waters of our estuaries and marshes, living in water from the low ride line to 40 feet. Oysters are sessile, which means they do not move about. They permanently adhere themselves to a hard object, most often other oysters, forming oyster beds, also known as rakes.Oysters change their sex repeatedly throughout their lives, depending upon the needs of the bed. One female can spawn 100 million eggs at a time, but probably only 10 of those make it to adulthood.
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- The oyster is a filter feeder, taking plankton, bacteria, and oxygen from the water. It is the filter feeding that leaves the clams (and all filter feeders) susceptible to pollution, and increased silt from dredging can suffocate the animals. This may play havoc with the ecosystem as filter feeders play an integral role in keeping our water ways clean. A single adult oyster can filter FIFTY gallons a water in a single day.
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- Unlike most shells, the oyster can vari widle in size, shape, and color.
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- Ribbed Mussel. Shells in which the brown periostracum (skin) has worn off will be yellow grey with purple tinges (actually quite pretty).
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- The Quahog Clam is a common sight on our natural beaches and tidal flats.The clam lives burrowed into the mud and sand of inlet bottoms. To feed, the clam extends a siphon through its open shell to the water above the mud.
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- The Quahog Clam is easily recognizable by its heavy shell, broadly oval shape, and a thick, prominent umbo, the hinged end.
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- Gone Clamming. If a Quahog can survive its predators, it can live 40 years, and grow to be over 6 inches long.
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- Ark shells are the most commonly found shell on HHI (followed by the oyster). There are numerous kinds, with often just small difference among them Here we have the Incongrous (center l & bottom) and the Cut-Ribbed (center r & top).
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- Blood Arks, In life arks are covered with a brown, fuzzy periostracum, or skin. The tumbling of the surf will wear this skin off over time. Arks may be up to 4 inches wide. Arks live burrowed in the mud, ranging from the tidal flats out to ocean depth.
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- But some arks are much more rarely found. The Turkey Wing Ark (top) and the Mossy Ark (bottom).
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- Giant Atlantic Cockle, reaching up to 5 inches in length, is the most common of seven species found on our shores. The Cockle is the “classic seashell.”
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- Channeled Duckclam
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- Easily found at the beach if you let your eyes stray to a bit of sparkle, the Common Jingle has brittle pearly-translucent shells with no obvious hinge. They live in shallow water attached to rocks or other shells.
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- Atlantic Razor Clam can be up to 6 inches in length and is 6 times longer than wide. These fast burrowers live in the sandy bottoms.
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- The Stout Tagelus is another type of razor clam, but is shorter, wider, and almost oval in shape.
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- Southern Surfclam
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- Angel Wing. A fragile shell that is not often found intact, but may be up to 8 inches in length. They live burrowed in the mud from the low tide line to a depth of 60 feet.
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- Coquina Clam and its trail. The intratidal zone, that area between the low and high tide points, is the habitat of the Coquina Clam. Coquinas are among the smallest shells found on the beach.
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- Spiny Jewelbox
