Hard Clam, Northern Quahog, Round Clam
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Veneridae, Genus: Mercenaria, Species: M. mercenaria · Veneridae (Venus Clams) · Bivalve (Clam); single valve (half-shell); oval to sub-trigonal shape
Species
Mercenaria mercenaria
Shell Type
Bivalve (Clam); single valve (half-shell); oval to sub-trigonal shape
Family
Veneridae (Venus Clams)
Size
Approximately 2 to 2.5 inches in diameter. This specimen appears to be an intermediate size, often referred to as a 'Cherrystone' in culinary terms. Adults can grow up to 5 inches.
Color & Pattern
The interior shows a characteristic deep violet or purple staining along the posterior margin, fading into a creamy white or greyish-white center. The exterior (partially visible) is a dull greyish-white with concentric growth rings. The purple coloration is a diagnostic marker for this species.
Rarity
Very Common. This is one of the most frequently found shells on the beaches of Myrtle Beach and the surrounding Grand Strand.
Habitat
Found in intertidal and shallow subtidal zones, typically buried in sandy or muddy substrates in bays, estuaries, and along protected coastlines.
Geographic Range
Western Atlantic coast, ranging from the Gulf of Saint Lawrence in Canada down to Florida and the Gulf of Mexico. Extremely common in the Carolinas.
Description
A thick, heavy, and durable bivalve valve. The shell is heart-shaped to oval with a prominent beak (umbo) pointing toward the anterior. The interior is smooth and porcelaneous, featuring a distinctively beautiful purple 'wampum' patch. The edge of the shell (the margin) features fine serrations or crenulations.
Key Features
Heavy, thick valve; deep purple interior staining; serrated inner margins; heart-shaped profile; distinct concentric growth lines on the exterior.
Collector Value
Low monetary value due to its abundance, but high educational and historical interest. Specimens with deep, saturated purple patches are favored for jewelry making and craft work.
Condition Notes
Fair to Good. The shell shows significant erosion, likely from being tumbled in the surf. There is a prominent 'drill hole' near the hinge, which is evidence of a predatory gastropod (like a Moon Snail) boring through to eat the clam. The purple pigment remains vibrant.
Interesting Facts
The purple part of these shells was used by Native Americans (such as the Wampanoag and Narragansett) to create purple 'Wampum' beads, which were used for storytelling, ceremonial gifts, and later as a form of currency during early European trade.
Ecological Role
They are vital filter feeders that help maintain water clarity by consuming phytoplankton. They serve as a major food source for sea stars, moon snails, crabs, and humans. The species is commercially managed to prevent overharvesting.
Similar Species
Southern Quahog (Mercenaria campechiensis) is very similar but usually lacks the deep purple interior staining and has a more rounded shape.
Beach Finding Tips
Look along the wrack line or at low tide after a storm. They are often found half-buried in the sand. In Myrtle Beach, look for the 'purple flashes' in the shell piles near the water's edge.
Notes
Myrtle Beach SC