Prickly Cockle, Rose-flecked Cockle
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Trachycardium, Species: T. egmontianum · Cardiidae (Cockle family) · Bivalve (two-shelled). This specimen is a single valve (either left or right) with a fan-like, ovate shape.
Species
Trachycardium egmontianum
Shell Type
Bivalve (two-shelled). This specimen is a single valve (either left or right) with a fan-like, ovate shape.
Family
Cardiidae (Cockle family)
Size
Approximately 1.5 to 2 inches in length. This is an average sized specimen for the species, which typically grows between 1 and 2.5 inches.
Color & Pattern
Base color is a creamy white to pale grey. It features distinctive pinkish-rose to reddish flecks and blotches, primarily on the posterior margin and towards the umbo. The interior of these shells is typically stained with vibrant salmon, pink, or purple, though only the exterior is fully visible here. The color appears natural and well-preserved.
Rarity
Common; frequently found on beaches throughout its range, especially after storms or high tides.
Habitat
Marine; found in shallow waters from the intertidal zone to depths of about 30 meters. They prefer sandy or muddy substrates where they can burrow just below the surface.
Geographic Range
Western Atlantic, ranging from North Carolina south through Florida, the Gulf of Mexico, and the West Indies to Brazil.
Description
This is a sturdy, heart-shaped (when viewed as a pair) bivalve. It features 27-31 strong radial ribs. The ribs are decorated with small, sharp, scale-like imbrications or prickles, which are more pronounced on the posterior slope. The growth lines are visible but secondary to the prominent ribbing. The margin is deeply crenulated, matching the ends of the radial ribs.
Key Features
The most diagnostic feature is the 'prickly' texture created by the small scales on the ribs, combined with the distinctive rose or salmon-colored flecking on a white background. The ovate, slightly asymmetrical shape also distinguishes it from other cockles.
Collector Value
Low to Moderate; while beautiful, its commonness makes it a starter shell for most collectors. However, perfectly paired valves with vibrant interior coloring and intact scales are highly desirable for aesthetic displays. Typical value is $1-$5.
Condition Notes
The shell is in Good to Fine condition. The ribs and scales are mostly intact, though there is slight smoothing near the umbo (beaked end), which is common for beach-found specimens. The colors are still vivid. There are no obvious predator bore-holes.
Interesting Facts
The common name 'Cockle' comes from the Old French 'coquille', meaning shell. These animals have a strong, muscular foot that allows them to 'leap' across the sandy bottom to escape predators like starfish.
Ecological Role
Suspension feeders; they filter plankton and organic detritus from the water column, helping to clarify the water. They are a prey source for larger gastropods, sea stars, and shorebirds.
Similar Species
Yellow Cockle (Dasycardium muricatum) which usually lacks the pink flecks and is more yellowish; Giant Atlantic Cockle (Dinocardium robustum) which is much larger and smoother.
Beach Finding Tips
Look for these along the wrack line (the line of debris left by high tide) on sandy Gulf or Atlantic beaches. They are easiest to find after a period of onshore winds or heavy surf.