Giant Atlantic Cockle (also known as the Egg Cockle)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Acanthocardia, Species: Acanthocardia tuberculata · Cardiidae (Cockle family) · Bivalve (two-shelled clam), whole shell, symmetrical fan or heart-like shape when viewed from the side, dome-like radial profile.
Species
Acanthocardia tuberculata
Shell Type
Bivalve (two-shelled clam), whole shell, symmetrical fan or heart-like shape when viewed from the side, dome-like radial profile.
Family
Cardiidae (Cockle family)
Size
Approximately 2 to 3 inches in width, which is average for this species. Adults typically range from 2 to 4 inches.
Color & Pattern
Rich earthy brown base color featuring darker brown or greyish concentric bands and subtle radial striping. The colors appear natural and well-preserved with distinct growth lines intersecting strong radial ribs.
Rarity
Common, frequently discovered by beachcombers along European and Mediterranean coastlines.
Habitat
Found in shallow marine waters, typically inhabiting sandy or muddy sand substrates in the intertidal and subtidal zones down to moderate depths.
Geographic Range
Eastern Atlantic Ocean, ranging from the British Isles and the Mediterranean Sea down to the coast of West Africa, perfectly matching the provided origin of Lagos, Portugal.
Description
This is a robust and attractive bivalve shell characterized by a high, rounded, dome-like profile. The exterior is heavily sculpted with prominent, radiating ribs that create a finely scalloped margin along the edge. Concentric growth stages are clearly visible as darker bands across the radial ribs, giving it a rustic, textured appearance.
Key Features
High radial rib count, distinct rounded apex, robust symmetrical structure, and a deeply scalloped ventral margin where the ribs terminate.
Collector Value
Low to moderate value. While widely available and affordable, large, flawless, gem-quality specimens with exceptional coloration remain popular additions to starter and intermediate conchology collections.
Condition Notes
Good condition with minor natural wear on the apex. The strong radial ribs and pattern are well-preserved, though minor fading is present consistent with a beach-collected specimen. Collectibility grade is Good.
Interesting Facts
Cockles are capable of using their muscular, sickle-shaped foot not only for burrowing rapidly into the sand but also to leap away from approaching predators like starfish.
Ecological Role
As filter feeders, cockles play an essential role in clearing organic particles from the water column, and they serve as an important food source for numerous fish, shorebirds, and marine mammals.
Similar Species
Acanthocardia echinata (Prickly Cockle), which features sharper, more pronounced spine-like projections along the ribs compared to the smoother radial ribs of A. tuberculata.
Beach Finding Tips
Look along sandy European and Mediterranean beaches at low tide, particularly after storms or heavy wave action that uncovers buried bivalves in the surf zone.
Notes
Lagos Portugal