Atlantic Surf Clam (also known as Bar Clam, Skimmer Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Mactridae, Genus: Spisula, Species: Spisula solidissima · Mactridae (Trough shell family) · Bivalve (two-shelled), whole shell (smooth triangular-ovate shape)
Species
Spisula solidissima
Shell Type
Bivalve (two-shelled), whole shell (smooth triangular-ovate shape)
Family
Mactridae (Trough shell family)
Size
The prominent triangular specimen shown at the lower left measures approximately 2 inches in length, which is a medium-sized specimen. Adults of this species typically range from 4 to 7 inches, with exceptionally large individuals reaching up to 8 inches.
Color & Pattern
The exterior features a creamy off-white to pale yellowish-tan base color with concentric growth lines. The periostracum is mostly worn away, revealing a smooth, matte calcareous surface. The interior is a clean, polished white with a distinct pallial sinus and hinge teeth.
Rarity
Very Common
Habitat
Found buried in coarse sand and fine gravel in the shallow subtidal and intertidal zones of high-energy ocean beaches and surf zones.
Geographic Range
Western Atlantic Ocean, extending from the Gulf of St. Lawrence in Canada down to Cape Hatteras, North Carolina, and occasionally further south into the Carolinas.
Description
A classic, sturdy bivalve shell with a robust, equilateral triangular-oval outline. The exterior displays fine, concentric growth lines marking the cycles of expansion. The beaks (umboes) are prominent and located near the center. The interior possesses a strong hinge plate with prominent cardinal and lateral teeth designed to withstand heavy surf action.
Key Features
Solid, heavy triangular-oval shell, central umbo, lack of prominent external radial ribs (unlike cockles or scallops), and strong internal hinge teeth characteristic of the Mactridae family.
Collector Value
Low commercial value as they are extremely common beachcast items along the mid-Atlantic coast, though large, pristine specimens with intact periostracum are kept by beginner beachcombers.
Condition Notes
Good condition. The shell is intact with minor edge wear consistent with wave action in the Outer Banks surf. The interior is clean and the structural integrity is sound. Grade: Good.
Interesting Facts
The Atlantic Surf Clam is commercially important for the seafood industry, frequently harvested for clam strips and chowder. They are rapid burrowers and can quickly rebury themselves if dislodged by rough waves.
Ecological Role
Plays a vital benthic role by filtering organic particles from the water column. Serves as an important prey source for sea stars, moon snails, gulls, and various fish species.
Similar Species
Stout Tagelus (Tagelus plebeius) or Oval Venus (Mercenaria species), distinguished primarily by the distinct triangular geometry and heavy hinge structure of Spisula solidissima.
Beach Finding Tips
Look along high-energy Atlantic-facing barrier island beaches like the Outer Banks, North Carolina, particularly at low tide or immediately following heavy storms and rough surf conditions.
Notes
North Carolina kill devils hill outer banks