Atlantic Surf Clam (also known as Hen Clam, Bar Clam, or Sea Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Mactrida, Family: Mactridae, Genus: Spisula, Species: S. solidissima · Mactridae (Surf clams or Trough shells) · Bivalve (single valve shown). Sub-triangular, ovate shape.
Species
Spisula solidissima
Shell Type
Bivalve (single valve shown). Sub-triangular, ovate shape.
Family
Mactridae (Surf clams or Trough shells)
Size
Approximately 35-50mm in width based on visual scale. This is a juvenile specimen; adults typically reach 150-200mm (6-8 inches).
Color & Pattern
Creamy white to light tan base. Features prominent concentric growth rings in brownish-grey. The surface shows a slightly weathered periostracum remnants near the margins and a sun-bleached look toward the umbo.
Rarity
Very Common. These are among the most frequently found shells on mid-Atlantic United States beaches.
Habitat
High-energy marine environments. Found in the subtidal zone from just below the low-tide mark to depths of 30 meters, typically buried in clean sand.
Geographic Range
Western Atlantic Ocean, ranging from Nova Scotia, Canada, to Cape Hatteras, North Carolina.
Description
Strong, thick-walled valve with a broadly triangular shape. The exterior surface is smooth except for the concentric growth lines. The umbo (beak) is central and slightly tilted forward. This specimen represents a robust, heavy-shelled species designed to withstand turbulent surf zones.
Key Features
Characteristic sub-triangular shape; large, deep chondrophore (internal hinge pit) visible if flipped; smooth surface lacking radial ribs; heavy shell weight compared to similar-sized bivalves.
Collector Value
Low monetary value due to extreme abundance, but often kept by casual collectors for their classic 'seashell' aesthetic. Pristine, giant specimens over 7 inches or matched pairs are more desirable.
Condition Notes
Good. The valve is intact with no major chipping on the ventral margin. Some surface erosion and bleaching are present, indicating it spent time in the wrack line before being collected. Overall collectibility grade: Fine.
Interesting Facts
This species is the primary source of 'clam strips' in the United States. They have a massive muscular foot used for rapid burrowing to escape the heavy pounding of waves in the surf zone. They can live up to 30 years and are significant indicators of ocean health.
Ecological Role
A major filter feeder that helps clarify coastal waters. They are a vital food source for moon snails, crabs, sea stars, and various bottom-dwelling fish like cod and flounder.
Similar Species
Spisula ovalis (Southern Surf Clam) which is smaller and more oval; Mactromeris polynyma (Arctic Surf Clam) which has more prominent hinge teeth.
Beach Finding Tips
Best found after heavy storms or 'nor'easters' which wash them up from offshore sandbars. Look at the high-tide line on wide, sandy Atlantic beaches during a receding tide.