Atlantic Surf Clam (also known as Beach Clam or Skimmer)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Mactridae, Genus: Spisula, Species: Spisula solidissima · Mactridae (Trough shell family) · Bivalve, whole shell, triangular to sub-triangular shape
Species
Spisula solidissima
Shell Type
Bivalve, whole shell, triangular to sub-triangular shape
Family
Mactridae (Trough shell family)
Size
Approximately 2.5 to 3 inches in length, which is a medium size for this species. Adults typically range from 4 to 7 inches, with some exceptional specimens reaching up to 8 inches.
Color & Pattern
The exterior is mostly sun-bleached chalky white with faint traces of brownish-yellow near the posterior margin and umbo. The interior is smooth, glossy white. The natural periostracum has been completely worn away due to beach tumbling.
Rarity
Very Common, frequently encountered washed ashore on sandy beaches after storms or rough surf.
Habitat
Found buried in sandy substrates in the surf zone and shallow subtidal waters, ranging from the low intertidal zone down to depths of about 130 feet (40 meters). Marine environment.
Geographic Range
Western Atlantic Ocean, extending from the Gulf of St. Lawrence in Canada down to Cape Hatteras and South Carolina in the United States, very common along the mid-Atlantic coast.
Description
A sturdy, heavy, sub-triangular bivalve shell with a smooth, chalky exterior surface. It features prominent growth lines concentric to the umbo, which is located slightly anterior to the center. The margins are smooth, and the interior reveals strong hinge teeth characteristic of the Mactridae family.
Key Features
Sub-triangular to oval-triangular outline, heavy and solid construction, prominent internal cardinal and lateral hinge teeth, and a smooth ventral margin without crenulations.
Collector Value
Low collector value due to extreme commonness, though larger, pristine specimens with intact periostracum are valued by beginner shell collectors. Generally not sold as a high-end collector piece.
Condition Notes
Good condition overall as an intact single valve, though it is heavily sun-bleached with a chalky texture and worn exterior typical of beach-cast specimens. Collectibility grade is Good.
Interesting Facts
The Atlantic Surf Clam is commercially harvested on a large scale for the food industry, primarily for clam strips and chowder. They can use their muscular foot to dig rapidly back into the sand if exposed by shifting waves.
Ecological Role
Serves as an important prey item for sea stars, predatory snails, crabs, and bottom-feeding fish such as rays and sharks. They are filter feeders that help clean coastal waters by consuming phytoplankton.
Similar Species
Stout Tagelus (Tagelus plebeius) which is much more elongated, or other surf clams like Mactromeris polynyma (Arctic Surf Clam) which has a darker, more prominent periostracum.
Beach Finding Tips
Look along high tide lines on exposed sandy ocean beaches, especially following stormy weather or rough sea conditions when shifting sands uncover buried shells.
Notes
Outer banks, North Carolina on Kill Devils Hill beach