Pacific Egg Cockle (also known as the Hawaiian Strawberry Cockle or Egg Cockle)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Fragum, Species: Fragum mundum · Cardiidae (Cockle family) · Bivalve (two-shelled clam), whole shell valve, fan or sub-oval disc shape
Species
Fragum mundum
Shell Type
Bivalve (two-shelled clam), whole shell valve, fan or sub-oval disc shape
Family
Cardiidae (Cockle family)
Size
Approximately 0.5 to 0.75 inches, which is typical for this species. Adults generally range from 0.5 to 1.0 inch.
Color & Pattern
Predominantly creamy white to pale yellowish-tan with subtle brownish concentric markings or bands near the margins. The coloration is natural and shows slight beach-wear.
Rarity
Common, frequently found by beachcombers in the Hawaiian islands.
Habitat
Shallow subtidal and intertidal zones, typically found buried in clean sandy substrates, sand pockets in coral reefs, and shallow seagrass beds.
Geographic Range
Indo-Pacific region, including Hawaii (Oahu), Polynesia, and stretching across the tropical Indian and Pacific oceans.
Description
A charming and sturdy small bivalve featuring a plump, rounded profile with prominent, raised radial ribs that create a distinct serrated margin. The concentric growth lines intersect with the ribs to form a subtle, beaded or reticulated texture. The hinge line is compact, and the overall shape resembles a tiny inflated heart when viewed from the side with both valves joined.
Key Features
Inflated, rounded-oval profile; strong radial ribs with fine transverse sculpturing giving a textured, beaded appearance; distinct heart-shaped profile when viewed from the anterior or posterior with paired valves.
Collector Value
Low to moderate commercial value, but highly popular among local beachcombers and shell crafters in Hawaii for making traditional shell jewelry such as Niihau-style or Hawaiian shell leis.
Condition Notes
Good condition single valve. Shows minor natural wear along the edges from wave action, but retains its structural integrity and primary surface sculpture. Collectibility grade: Good.
Interesting Facts
Cockles are capable of a surprising method of locomotion using a strong, muscular, sickle-shaped foot. Instead of just burrowing, they can use this foot to leap or vault across the sand to escape predators like predatory snails and crabs.
Ecological Role
Cockles serve as important filter feeders in benthic marine ecosystems, helping to clear suspended organic particles from the water column. They are a staple food source for various bottom-feeding fish, rays, and carnivorous gastropods.
Similar Species
Fragum unedo (Strawberry Cockle), which is typically larger, more elongated, and features brighter red or pinkish coloration with more prominent scale-like projections on the ribs.
Beach Finding Tips
Look along sandy beaches on Oahu, particularly in the wrack line left by high tides or storm surges. Sifting through fine shell drift in shallow bays and coves often yields well-preserved single valves.
Notes
Oahu