Atlantic Cockle (also known as Common Cockle)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Dinocardium, Species: Dinocardium robustum · Cardiidae (Cockle family) · Bivalve (two-shelled clam), whole single valve, fan/heart-shaped disk
Species
Dinocardium robustum
Shell Type
Bivalve (two-shelled clam), whole single valve, fan/heart-shaped disk
Family
Cardiidae (Cockle family)
Size
Approximately 1.5 to 2 inches in width, which is a medium size for this specimen. Full adult specimens typically range from 2 to 4 inches.
Color & Pattern
Cream to whitish base color decorated with brownish-orange to reddish-brown radial streaks and blotches, particularly concentrated toward the posterior margin. The colors are natural and show mild weathering consistent with beach collection.
Rarity
Common, frequently found by beachcombers along the southeastern United States and Gulf coastlines.
Habitat
Shallow marine waters in sandy substrates, typically found living buried just beneath the surface in intertidal and shallow subtidal zones along sandy beaches and protected bays.
Geographic Range
Western Atlantic Ocean, extending from Virginia south through Florida, the Gulf of Mexico, and into the Caribbean.
Description
An attractive, sturdy bivalve shell featuring prominent, evenly spaced radial ribs that create a deeply scalloped margin. The umbo is slightly curved, and the exterior exhibits classic cockle symmetry with vibrant brownish-orange markings over a pale background.
Key Features
Strongly inflated, heart-shaped profile when viewed from the side, distinctive heavy radial ribs numbering around 32 to 36, and lack of internal teeth on the hinge compared to some other bivalves.
Collector Value
Low to moderate commercial value. While widely appreciated by beginner beachcombers and decorative crafters, pristine pairs with full color fetch modest prices in shell shops.
Condition Notes
Good overall condition for a beach-collected single valve. Minor surface wear and sand residue are present, but the radial ribs and margins remain largely intact with good retention of the original color pattern. Collectibility grade is Good.
Interesting Facts
Cockles are capable of a remarkable leaping locomotion using their muscular, sickle-shaped foot to escape predators like starfish and carnivorous snails.
Ecological Role
Serves as an important prey item for various marine predators including large fish, rays, and channeled whelks. As filter feeders, they help clarify coastal waters by consuming suspended phytoplankton.
Similar Species
Prickly Cockle (Trachycardium muricatum), which features much sharper, spine-like projections along the ribs, and the Yellow Cockle (Laevicardium laevigatum), which is smoother and lacks the prominent rough ribs.
Beach Finding Tips
Look along high tide wrack lines on sandy ocean beaches, especially following storms or rough surf conditions. Single valves are frequently cast ashore.