Heart Cockle, Heart Shell, or Mediterranean Heart Cockle
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Corculum, Species: Corculum cardissa · Cardiidae (Cockle family) · Bivalve (two-shelled), whole shell, heart-shaped disc
Species
Corculum cardissa
Shell Type
Bivalve (two-shelled), whole shell, heart-shaped disc
Family
Cardiidae (Cockle family)
Size
Approximately 2 to 2.5 inches in width and height, which is a standard size for adult specimens; adults typically range from 1.5 to 3 inches.
Color & Pattern
Predominantly creamy white to pale yellowish-white throughout, showing some minor sun-bleaching. The surface features radial ribs decorated with tiny bead-like nodes, and slight pinkish or brownish tinting near the prominent umbo.
Rarity
Common to Uncommon, frequently collected by divers and beachcombers within its native Indo-Pacific range.
Habitat
Found in shallow tropical waters, typically in coral reef environments, sandy patches among reefs, and clear seagrass beds down to depths of about 20 meters.
Geographic Range
Indo-Pacific region, ranging from the Red Sea and East Africa across the Indian Ocean to Southeast Asia, northern Australia, and the western Pacific islands.
Description
This exquisite bivalve is remarkably compressed laterally and shaped precisely like a symmetrical botanical heart when viewed from the side. The exterior features pronounced radial ribs embellished with delicate crenulations and small scale-like nodes. The margins are deeply scalloped, matching up tightly when both valves are closed.
Key Features
Distinguished by its distinctively compressed, highly flattened heart-like profile, prominent central umbo, and finely sculpted radial ribs with beaded textures.
Collector Value
Moderately high desirability among casual and advanced collectors due to its charming, unmistakable heart shape. Common specimens are affordable and widely available in shell shops.
Condition Notes
Good condition. The shell is intact with both valves joined, displaying mild sun-bleaching and minor wear on the surface but retaining clear sculptural details and a strong hinge.
Interesting Facts
Unlike many bivalves, Corculum cardissa often hosts symbiotic single-celled algae (zooxanthellae) within its tissues, similar to corals, requiring sunlight for nourishment through photosynthesis.
Ecological Role
Serves as a vital food source for various carnivorous marine species including fish and gastropods. Its symbiotic relationship with algae links it closely to the health of coral reef ecosystems.
Similar Species
Other species within the genus Corculum, such as Corculum impressum or Corculum humanum, which vary slightly in ribbing density, flatness, and contour.
Beach Finding Tips
Best found by snorkeling or diving in shallow Indo-Pacific reef flats and sandy lagoons, or by searching high-tide shell lines on tropical coral sand beaches following storms.