Strawberry Cockle (Fragmentary)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Fragum, Species: Fragum fragum · Cardiidae (Cockle family) · Bivalve (clams/two-shelled); this specimen is a shell fragment or a heavily eroded single valve.
Species
Fragum fragum
Shell Type
Bivalve (clams/two-shelled); this specimen is a shell fragment or a heavily eroded single valve.
Family
Cardiidae (Cockle family)
Size
Approximately 2-3 cm (0.8-1.2 inches). Most adults reach 3-5 cm. This fragment represents about 40-60% of a full valve.
Color & Pattern
Base color is an off-white to cream. It displays characteristic brownish-orange to tan splotches along the ribs. The color appears natural but slightly faded due to beach erosion and sun bleaching.
Rarity
Common; while whole specimens are frequent on these beaches, this specific fragment is very common beach material.
Habitat
Sandy bottoms in shallow, warm tropical and subtropical waters, typically found in intertidal zones or shallow reefs.
Geographic Range
Indo-Pacific region, including Northern and Eastern Australia (consistent with Sandgate/Brighton Beach area in Queensland).
Description
A triangular fragment of a bivalve valve. The surface features strong radial ribbing, a hallmark of the cockle family. The ribs are prominent and separated by narrow grooves. The shell has a thick, sturdy structure providing a slightly porcelain-like texture, though it is currently matte due to weathering.
Key Features
Distinguished by the concentrated radial ribs and the specific yellowish-tan spotting found on the ridges of the ribs. The fragment shows a slightly 'weighted' corner which suggests the sharply angled posterior characteristic of the genus Fragum.
Collector Value
Minimal financial value due to the fragmentary condition. It serves primarily as a 'study piece' or beach remembrance rather than a specimen for a high-end collection.
Condition Notes
Poor to Fair (fragmentary). The shell is incomplete, missing the hinge and the majority of the margin. There are small pitting marks likely caused by boring organisms (clionid sponges) or acidic erosion from sand burial.
Interesting Facts
The genus Fragum is unique because some species host symbiotic algae (zooxanthellae) in their mantle tissues, similar to giant clams, which help provide nutrients through photosynthesis.
Ecological Role
Suspension feeders that filter plankton from the water column. They are an important food source for shorebirds, rays, and larger predatory gastropods.
Similar Species
Fragum unedo (Pacific Strawberry Cockle) which is larger and usually has redder markings; Vasticardium species which are more rounded and lack the sharp posterior angle.
Beach Finding Tips
Best found after high tide or a storm on sandy mudflats like those at Sandgate. Look for the white glint against the darker sand during low tide near the seagrass beds.
Notes
Brighton beach sandgate