Atlantic Surf Clam (also known as Hen Clam, Bar Clam, or Skimmer Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Mactridae, Genus: Spisula, Species: solidissima · Mactridae (Surf Clam or Trough Shell family) · Bivalve (single valve shown). Triangular/ovate shape with a thick, sturdy structure.
Species
Spisula solidissima (Confidence: 95%)
Shell Type
Bivalve (single valve shown). Triangular/ovate shape with a thick, sturdy structure.
Family
Mactridae (Surf Clam or Trough Shell family)
Size
Approximately 4.5 to 5.5 inches in width. This is a mature adult specimen; the species can grow up to 8 inches (20 cm).
Color & Pattern
Uniform chalky white to off-white exterior. The natural brownish-yellow periostracum (outer skin) has been completely eroded or cleaned away, leaving a smooth, calcified surface typical of beach-worn specimens.
Rarity
Very Common. These are among the most frequently found large shells on beaches in the Northeastern United States.
Habitat
Marine; found in the high-energy surf zone and subtidal waters from the shoreline down to depths of 100 feet. They prefer clean, sandy substrates.
Geographic Range
Western Atlantic, ranging from Nova Scotia, Canada, southward to Cape Hatteras, North Carolina.
Description
An attractive, robust, and heavy triangular shell. The exterior is marked by concentric growth lines and a smooth, slightly dull finish. The hinge area is thick with a characteristic spoon-shaped internal pit (chondrophore) where the ligament sits. The margins are smooth and the valves are nearly equilateral.
Key Features
Triangular shape with a central, prominent beak (umbo); large, deep spoon-shaped pit in the hinge; lack of radial ribs; very thick and heavy shell wall compared to other white clams.
Collector Value
Low ($1 - $5). While visually appealing due to their clean white color and symmetry, they are too common to have high monetary value. They are primarily valued as decorative items or 'beginner' finds for beachcombers.
Condition Notes
Fair to Good. The shell is beach-worn and sun-bleached, losing its organic outer layer. The edges show slight chipping (chipped margin), common for shells tossed in the surf. It lacks the second valve and the interior ligament.
Interesting Facts
The Atlantic Surf Clam is the primary species used for 'fried clam strips' and canned chowder in the United States. They are powerful burrowers, using a large muscular foot to dive into the sand to escape predators and strong waves.
Ecological Role
Suspension feeders that filter plankton from the water column. They are a vital food source for sea stars, moon snails, gulls, and larger fish like cod; their population is managed by federal fisheries.
Similar Species
Mactromeris polynyma (Arctic Surf Clam), which is usually smaller and found in colder waters, and Mactra stultorum (Rayed Trough Shell), which has distinct colorful rays.
Beach Finding Tips
Best found after heavy storms or 'Nor'easters' along the Jersey Shore, Long Island, and Cape Cod. Look for them at the low tide line where heavy debris settles.