Category Archives: Atlantic Seashore

Washed Ashore: Soft-shelled Clam

Photo of Soft-shelled Clam

Soft-shelled Clams (Mya arenaria) are among the best known marine mollusks harvested from mud flats throughout New England. Also known as Long-necked or Steamer Clams, these shellfish are food for many species, including Atlantic Moon Snails, Green Crabs, various gulls and diving ducks, certain fish, Northern Raccoons, and, of course, humans.

The two halves of this bivalve's shell are similarly shaped, with the exception of the hinge area. The left valve has a spoon-like shelf, and the right valve has a corresponding groove to accommodate it.

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Mammals: Harbor Seal

Photo of Harbor Seals

Harbor Seals (Phoca vitulina) live along the New England coast where they eat a variety of fish, shellfish, and other marine life. They often bask in small groups on rock ledges or sandbars, especially at low tide, and I've been pleasantly surprised a number of times to see the head of one pop into view while scanning for seabirds in a coastal harbor or off a sandy or rocky beach. Looking into their dark eyes always gives me pause.

Harbor Seals are more common and quite a bit smaller than the longer-nosed Gray Seals. One way to tell the two apart is by looking at their nostrils. Gray Seals have spaced out nostrils, whereas the nostrils of Harbor Seals are close together and form a v-shape. To learn more about Harbor Seals, visit Animal Diversity Web.

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Low Tide Life: Atlantic Plate Limpet

Photo of Atlantic Plate Limpet

Along the New England coastline, the only limpet who spends time in the intertidal zone is the Atlantic Plate Limpet (Testudinalia testudinalis). Also known as Tortoiseshell Limpets, these marine snails are typically no more than an inch long, so spotting them requires up close exploration.

Photo of Atlantic Plate Limpet

I've occasionally encountered them while winkling at low tide in and around rocky tide pools. These snails prey on red algae; Atlantic Dogwinkles are among their predators.

Photo of Atlantic Plate Limpet

Low Tide Life: Northern Moon Snail

Photo of Northern Moon Snail

Back in August, while wading in knee-deep water at a local beach, I noticed dozens if not hundreds of Northern Moon Snails (Euspira heros) slowly plowing through the sand. Having been familiar with their shells (empty, washed-ashore ones, that is) for years, I was thrilled to find some occupied dwellings.

The almost transparent bodies of Northern Moon Snails appear much too big for their shells, but as I experienced first hand, when picked up, individuals push water out of their shells and bodies and manage to squeeze into their nearly round homes without much trouble. A perfectly sized, flat operculum serves as the snug door a snail shuts to complete this marine magic trick.

These mollusks live in intertidal and, more commonly, subtidal waters along the New England coastline (and elsewhere) where they seek out meals in the form of Atlantic Surf Clams and other shellfish.

Bonus quiz: Find and identify the other mollusk in one of the following photos.

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Low Tide Life: Smooth Periwinkle

Photo of Smooth Periwinkle

Smooth Periwinkle (Littorina obtusata) is a small mollusk of the New England coastline who lives in association with Knotted Wrack, Bladder Wrack, and other types of marine algae. Smooth Periwinkle's nearly flat spire is distinctive among local periwinkles. Most of the individuals I've noticed have been yellow (another common name for this species is Northern Yellow Periwinkle), but shell color is variable, and may instead be red, brown, green, or multi-colored. To learn more about this mollusk, check out this species ID card offered by the Gulf of Maine Research Institute.

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