Bear Paw Clam, Horse's Hoof Clam, Strawberry Clam
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae (subfamily Tridacninae), Genus: Hippopus, Species: Hippopus hippopus · Cardiidae (Tridacninae subfamily - Giant Clam family) · Bivalve (two-shelled). The specimen shown is a single valve (one half), characterized by a heavy, thick, elongated-triangular fan shape with deep radial ribbing.
Species
Hippopus hippopus
Shell Type
Bivalve (two-shelled). The specimen shown is a single valve (one half), characterized by a heavy, thick, elongated-triangular fan shape with deep radial ribbing.
Family
Cardiidae (Tridacninae subfamily - Giant Clam family)
Size
Approximately 5 to 7 inches in length. This is a medium-sized specimen; adults can reach up to 16 inches (40 cm), though 8-10 inches is most common in many collections.
Color & Pattern
Base color is an off-white to creamy white. It features distinctive reddish-purple or strawberry-pink transverse bands and blotches arranged in irregular rows across the radial ribs. The interior (though not fully visible) is typically porcelain white with yellow flushes on the muscle scars.
Rarity
Common in specialized ecosystems but regulated. As a beach find, it is uncommon to rare depending on the proximity to protected reef zones. In the trade, it is widely available but strictly monitored.
Habitat
Shallow tropical marine waters, typically found on coral reef flats or sandy substrates near reefs at depths of 0 to 6 meters. Often found in seagrass beds or resting unattached on the sand.
Geographic Range
Indo-West Pacific region, ranging from the Andaman Islands eastward to the Philippines, Indonesia, and northern Australia, and extending toward the Marshall Islands.
Description
A robust, heavy, and thick-walled bivalve. The shell features approximately 13 to 14 prominent, rounded radial ribs covered in tubular, scale-like protrusions (though these are often worn down in beach-worn specimens). The shape is unique among giant clams, resembling the hoof of a horse or the paw of a bear, with a relatively narrow byssal opening compared to Tridacna species.
Key Features
Heavy weight relative to size; distinctive reddish-pink dashed patterns; tightly interlocking zig-zag ventral margins; and a narrow, closed byssal gape that distinguishes it from the Tridacna genus.
Collector Value
Low to Moderate ($10 - $40 USD depending on size and intensity of color). It is a popular 'aesthetic' shell but loses value when the sharp scales are worn away or the color is sun-bleached.
Condition Notes
Fair to Good. There is significant weathering and beach erosion visible on the ribs, with some dulling of the original reddish pigment. The edges show minor chipping, suggests it was tossed in the surf for some time. Collectibility is moderate for a reference specimen.
Interesting Facts
Like its cousins the Giant Clams, Hippopus hippopus hosts symbiotic algae called zooxanthellae in its mantle tissue, which provide the clam with nutrients via photosynthesis. Historically, the heavy shells were used as mortars for grinding or as decorative washbasins in various cultures.
Ecological Role
Primary producer/consumer due to symbiosis; provides habitat for small reef organisms. Under CITES Appendix II, trade is restricted to ensure sustainability, as they are vulnerable to overharvesting for food and the aquarium trade.
Similar Species
Hippopus porcellanus (China Clam) which is smoother and lacks the intense red spotting; Tridacna maxima, which has a much larger byssal opening and more pronounced, leaf-like scales.
Beach Finding Tips
Best found on low-tide reef flats in the Indo-Pacific. Look for 'dead' valves washed into the inner reef lagoons or caught in coral rubble after storm surges. Freshly washed specimens preserve the red color better.
Notes
I’m ass