Common Atlantic Cockle
Phylum Mollusca, Class Bivalvia, Order Cardiida, Family Cardiidae, Genus Dinocardium, Species Dinocardium robustum · Cardiidae (Cockle family) · Bivalve, whole shell, heart-shaped fan
Species
Dinocardium robustum
Shell Type
Bivalve, whole shell, heart-shaped fan
Family
Cardiidae (Cockle family)
Size
Approximately 2-3 inches, which is slightly smaller than average for this species. Adults typically range from 3 to 5 inches.
Color & Pattern
Warm brownish-tan base color with darker reddish-brown speckles and faint vertical banding following the ribs. The coloration appears natural and slightly weathered from beach tumbling.
Rarity
Common
Habitat
Found in shallow marine waters, primarily inhabiting sandy intertidal and subtidal zones down to about 60 feet, buried just beneath the sand in bays and protected coastal flats.
Geographic Range
Western Atlantic Ocean, ranging from Virginia down through Florida, the Gulf of Mexico, and the Caribbean.
Description
A robust, inflated bivalve shell featuring prominent, deeply carved radial ribs extending from the umbo to the scalloped margin. The shell has a distinct heart-shaped cross-section when viewed from the side and a strong, interlocking margin.
Key Features
Deeply impressed radial ribs numbering around 32 to 36, a distinctly inflated, asymmetrical heart-like profile, and a robust, heavy-set valve structure.
Collector Value
Very common and inexpensive, typically valued between $1 to $5. Highly popular with casual beachcombers and beginner shell collectors due to its durability and classic appearance.
Condition Notes
Good condition with some minor wear along the margins and umbo area due to natural beach transport. Retains most of its structural integrity and natural coloration, graded as Good to Fine.
Interesting Facts
Cockles are capable of leaping or escaping predators by using their strong, muscular foot to flick themselves backward across the sand.
Ecological Role
Serves as an important prey species for various marine organisms including whelks, rays, and sea birds, while filtering organic particles from the water column.
Similar Species
Yellow Cockle (Trachycardium muricatum), which is generally smaller, more elongated, and possesses sharper, more spiny ribs.
Beach Finding Tips
Look along high-tide wrack lines on sandy ocean beaches or sheltered bay shores, particularly after storms or heavy wave action.