Mollusks Sandy Hook, NJ 07732 - Bivalve Shells, oysters, wampum, pearls, coquinas, mercenaria, mya, ark shells - Dave Grant - Brookdale College Ocean Institute

Bivalve Shells - Mollusks
Click here for Univalves
Go to Sandy Hook C.S.I.

Only the Arthropods have more species than the Mollusks (The "Soft Ones") and there are thought to be 100,000 types. There are about 12,000 species of marine clams, or Pelecypods (Hatchet-foot). They differ from other animals by possessing a Mantle and muscular Foot. Each has two shells (or valves) which are held together by strong muscles, and the hatchet-like foot is used for digging. A fold in the body wall (The mantle) secretes the calcareous shell, and yearly growth rings allow you to determine the age of a shell. Most clams filter food like plankton from the water (suspension feeders) but a few are deposit feeders and use siphons to vacuum up food from the mud, like some snails do.

Live Ark shell feeding in the Sandy Hook Aquarium.

Some of the most common bivalves you will encounter are pictured above. (Clockwise from the top) : Arks ((Anadara), Soft clams (or Clams, Steamers, Gapers or Nannynose depending on where on the coast you are collecting) [Mya], Hard clams (Quahogs or chowder clams - With the purple "mother-of-pearl [Mercenaria]), Chestnut Astarte (Bottom), and our largest bivalve, the Surf clam (Spisula).	The tiny Gem clam (Gemma) is our smallest bivalve and easily overlooked.
The Gem clam is also one of the most common in some bays. Seen here with worm tubes.	The delicate Jingle shell (or Mermaid's toenail [Anomia]) is very common on the beach and grows attached to rocks and other shells. It sometimes matches the pattern of the shell it is attached to.
	Several species of ark shell are found, including the Transverse ark (Left) (Below, right) Most bivalves can produce a pearl if an irritant gets under the mantle. The hard clam sometimes produces a pearl that matches the purple color of layered in its shell and this can be polished into jewellery. Wampum or Wampumpeag was composed of purple and white beads made from quahog and whelk shell. (Below)
Oysters were much more abundant in the bay a century ago and were a major food resource. Recent and relict shells (Partially fossilised) are common. Many shells are pock-marked by boring sponges.	Pequot, Mohegan, Narragansett and Long Island tribes originally traded wampum to the English for guns. The Pequot War put the control of wampum into the hands of Massachusetts Bay Colonists.
Wampum is still used for making jewellery and is said to bring good luck.	It is said that in the late 1700's wampum could still be used to pay tuition at Harvard University
Look for the Blister pearl on this oyster (Above), and in the close-up view. (Right).
	Even the scallop is known to produce blister pearls. (Left)
There is quite a bit of individual variation among seashells. This hard clam has unusual stripes which are used as markers in aquaculture stock. For more information on shellfish aquaculture, click here.
	(Left) Growth rings, like those on a tree, are prominent features on the shell of most bivalves. Can you estimate the age of this oyster from the layers on its hinge? Most clams are burrowers. The False Angel Wing (Below, left) digs into marsh peat, and the Angel Wing (Below) in mud. Both clams (Below) are fragile and usually are found broken on the beach (Or in your pocket when you get home).

Coquinas (Donax) live at the surf line and between the pounding waves use their muscular foot to burrow into the sand like mole crabs to feed on microscopic creatures between the particles.	Live ones are are increasingly common at Sandy Hook.
	(Left) Razor clams (Ensis) live on the bay side and burrow rapidly into the mud for safety since their delicate shells offer little protection from predators. Both clams are edible and used for food. In the Canadian Maritimes razor clams are are called Couteaux de Mer; and south of New Jersey the tiny Coquinas are sometimes made into a Coquina stew.

Some bivalves are sessile and cannot move from where they first settled from the plankton, or are attached by threads to a rock or shell. Slipper shells are Univalves, a snail that is form-fitted to a spot (Above) and other creatures like the worms and jingle shells attach to it. Jungle shells (or mermaid's toenails) have a hole in one shell where they attach to the substrate (Above and right).	Jingle shells or "Mermaid's toenails" (Anomia) are one of our most abundant shells at Sandy Hook.
	(Left) Mussels like the Ribbed and Horse (Modiolus), and the Blue (Mytilus)and Horse, are anchored to the bottom with byssal threads, but they can adjust their position by sending out new threads.
Razor clams (Ensis) burrow in the sediments to escape and scallops move away from threats on the surface.	Scallops like the Deep Sea and smaller Bay scallop can jet water between their shells to move or escape predators like starfish.
(Below) Some beach finds that are found with the Mermaid's Toenails and mistaken for shells are the Mermaid's Purse (The egg case of a skate) and the Mermaid's necklace (Egg case of a whelk).	(Below) There is also plenty of flotsam and jetsam that washes up on the shore with seashells. Can you identify it and figure out where it came from?

	(Left) The dime-sized cross-hatched Lucine (Divaricella) is a rare find at Sandy Hook.
Bivalves are bothered by many creatures including the boring sponges.	Illuminated from below you can see that the holes in this surf clam go through the shell.
One of the many activities you can do with your seashells is classify them and put them on a shell board like these summer campers have done, or draw the anatomy of the clam. For more camp and shell activities, click here..
	Shells that should not be taken home are any ordnance from Sandy Hook's long military past. If any bullet shells or suspicious articles are found by your students, leave them alone and contact your trip leader or the park rangers (732-872-5900). For our recipe for Sandy Hook clam chowder, click here. For information on aquaculture, click here.