Newport This Week

Seashells by the Seashore

NATURE in the NEIGHBORHOOD

An Atlantic surf clam, Spisula solidissima, found at Second Beach. (Photos by Lauren Parmelee)

An Atlantic surf clam, Spisula solidissima, found at Second Beach. (Photos by Lauren Parmelee)

In my last column, we strolled from the beach parking lot through the dunes and down the sand to the waterline, admiring the plants and animals along the way. This week, we discuss shell collecting, which is a traditional beach pastime for people of all ages.

The hard outer shells of mollusks, such as snails, whelks, clams, oysters, scallops, and mussels, are made of calcium carbonate, which is produced by the animal as it grows. The shell is not living tissue, so when the animal dies, the shell is left behind for us to find or to be eventually worn down by the sea.

Bivalve mollusks, like clams, have two shells that protect the soft animal inside, and gastropods, like snails, have one.

On First and Second Beach, look for the large white shells of the Atlantic surf clam. These bivalves live in sand or mud from the low tide line to waters about 100 feet deep. They are slow-growing and can live up to 30 years. Try counting each ridge on the shell to age them.

Common slipper shells, Crepidula fornicata, prefer the quieter waters of the bay.

Common slipper shells, Crepidula fornicata, prefer the quieter waters of the bay.

After summer storms you can often find clams washed up on the beach. They are perfect for digging in the sand if you forgot your pail and shovel.

People dig up surf clams to make chowder, but if you find a live clam on the beach it is better to leave it for the gulls. The longer a mollusk lies in the sun, the more likely bacteria will grow. That’s why raw bars are always full of ice.

According to Rob Hudson, shellfish hatchery manager and adjunct professor at Roger Williams University, surf clams are just making an appearance in Rhode Island’s commercial aquaculture. They will be harvested when they are about the size of a steamer, so if you see “butter clams” on the menu of your local seafood joint, try them out.

If you are walking Third Beach or Rome Point, you can’t help but find common slipper shells, which prefer the quieter waters of the bay. These gastropods are oval-shaped, with a shelf on the underside that supports the internal organs. This shelf is what makes the shell look like a slipper or little boat.

Groups of individual slipper shells are often found heaped up and fastened together, with the larger, older females below and the smaller, younger males on top.

Groups of individual slipper shells are often found heaped up and fastened together, with the larger, older females below and the smaller, younger males on top.

When young, these gastropods move about using their foot, but by the time they reach maturity, they are anchored to a hard surface for the rest of their lives. Slipper shells are often found stacked up on top of each other, which is convenient for their interesting sex life.

According to Save The Bay’s “The Uncommon Guide to the Common Life of Narragansett Bay,” these snails start life as males, but waterborne hormones cause some to become female when they get older. If you find a stack of live slipper shells, the big ones on the bottom are females, the ones in the middle might have both male and female organs, and the smaller ones on top are male. After fertilization, the eggs are brooded under the female’s foot.

There is a small fishery for slipper shells, Hudson said, which are reported to be quite tasty when eaten raw.

Of course, much more prevalent in Rhode Island aquaculture is the American oyster, which takes about two years to grow into the “petite” size most often served in restaurants.

A stroll along the water’s edge at First Beach is perfect for shell hunting.

A stroll along the water’s edge at First Beach is perfect for shell hunting.

Oysters are bivalves, but the two halves are different sizes and it is uncommon to find them connected when you are beachcombing. The larger, thick side attaches to the substrate, which can be mud, sand, rocks, or other shells below the tide line. The two shells, or valves, are connected by a thick muscle that allows the shells to open when it relaxes so the oyster can feed, which it does by filtering seawater and ingesting phytoplankton.

While you probably will not find a pearl in a Narragansett Bay oyster, they are important water purifiers, removing toxins and bacteria as they filter feed. Oysters also provide food to other organisms, such as snails, crabs, and a beautiful red-billed shorebird called the American oystercatcher.

I highly suggest picking up a copy of “The Uncommon Guide to the Common Life of Narragansett Bay” at the Exploration Center and Aquarium this summer. There is so much to learn about salty habitats.

Nature lover Laureen Parmelee of Newport is senior director of education at the Audubon Society of Rhode Island.

Nature lover Laureen Parmelee of Newport is senior director of education at the Audubon Society of Rhode Island.

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