Sandy Hook, NJ - Univalve Shells - Mollusks Sandy Hook, NJ 07732 - snails, periwinles, moon snails, hermit crabs, oysters - Dave Grant - Brookdale College Ocean Institute

Sandy Hook's Univalve Shells - Molluscs
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Snail eggs and larvae hatching

Only the Arthropods have more species than the Molluscs (The "Soft Ones") and there are thought to be 100,000 types. There are about 40,000 species of marine snails or Gastropods (Stomach-foot). Most snails are nocturnal and are carnivores. Their ribbon-like tongue or Radula is unique and used to harpoon or drill into their prey. They are some of the most beautiful animals in the sea, but some like the cone shell of the South Pacific give a painful sting with their radula.

Close-up of a moon snail drill hole.
Note the growth rings around the drill hole.	"Drills" like the Moon Snail are predators on bivalves (Especially surf clams - Above) and sometimes cannibals to each other. They drill a tiny bevelled hole in the shell of their prey (Magnified on the Left) (Below, right) Two species are abundant here, the Common and larger Lobed Moon Snail (or Shark-eye). Fisherman's toenails, a trap door or Operculum (Below, right), and the egg case (Below, left) of the snail (Sand Collar) are common finds from the Moon Snail.
Click here to see eggs and larvae hatching from a sand collar	Click here to see eggs and larvae hatching

	(Above, left) Other Univalves from the deep water include the Knobbed, Ten-ridged and Waved Whelk. Oyster drills (Above and above) drill a straight hole into the shell of their prey. When a hermit crab takes over a snail shell and keeps it from being buried, Snail Fur (a Hydroid) can grow over the shell surface (Above). To read more about snail fur, click here. (Left) Tiny Mud and Basket Snails are common on the beach. Some snails like the Mud Snails (Below) can graze algae, scavenge dead fish or vacuum the sediments for detritus.
Mud snails are sometimes bothered by a worm that also can cause clam-diggers itch in shell-fishermen.
15x	30x
50x	(Above and left) Most snails deposit their eggs in protective cases (Below, right) like these attached to an oak leaf that washed into the bay. The young are safe in here until they are ready to hatch and move about.
Slipper or boat shells hold onto their eggs until they are ready to hatch, then disperse them into the water at night.	Mud snail eggs
	(Left) Our two largest Univalves, the Knobbed and Channelled Whelks, produce foot-long Mermaid's necklaces to protect their eggs until hatching time.
	A close-up of one of the nickel-sized sections of the mermaid's necklace reveals dozens of baby whelks.
	Sandy Hook's rarest snail is not found in the ocean but on land. It is a terrestrial species. Note how thin the shell is since it must be carried on land and up trees.
The live snail has a dark periostracum and is active during wet weather. They are regularly found moving at a snail's pace near the gun batteries in the fort area.
	(Left) Some univalves move very little. These flat slipper shells (Crepidula plana) grow form-fitted to the inside curve of the shell of a moon snail shell that is occupied by a hermit crab and actually are arched backwards. (Below) A slipper shell clinging to the aquarium side has yellow egg masses.
Always make certain that shells you collect at the beach are not living, have any flesh left inside or are the home of other sea creatures like hermit crabs. Give them the shake and sniff test before you put them in your collecting bag, and if you are in doubt, place them back in the ocean.

(Right) The predatory moon snail bores into a soft clam (Mya). To see video of one hunting, click on the snail image. Do you think you know enough to go beachcombing? Click here to take the shell quiz.
	Snails are some of the most beautiful creatures in the sea. They are also the homes for many other creatures. Make certain the ones you collect are not occupied by mud crabs, hermit crabs or snail fur. Beachcomber tip: Never rise your shells in bleach to clean them. You will damage the color and they will always smell like bleach. Make certain they are empty; then soak them in a bucket of water for a week or more to let nature do the work.
	Not all Molluscs have shells and on rainy days and mornings with a heavy dew, you can sometimes find slugs in wet areas like the gun batteries.
Shell-less gastropods are also called "sea slugs" and can breathe through club-like cerata.
Eubranchus nudibranch ("naked gill") species.	Sea butterflies or pteropods. See coastal and arctic plankton.

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