Fluted Giant Clam (also Scaly Clam or Small Giant Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Subfamily: Tridacninae, Genus: Tridacna, Species: Tridacna squamosa · Cardiidae (Cockle family); Subfamily Tridacninae (Giant Clam family) · Bivalve; single valve (half-shell) present in the image. Shape is fan-like or semi-circular with deep undulations.
Species
Tridacna squamosa
Shell Type
Bivalve; single valve (half-shell) present in the image. Shape is fan-like or semi-circular with deep undulations.
Family
Cardiidae (Cockle family); Subfamily Tridacninae (Giant Clam family)
Size
Based on the window sill scale, this specimen appears to be approximately 6-8 inches (15-20 cm) in width. This is a mid-sized juvenile/young adult; the species can reach up to 16 inches (40 cm).
Color & Pattern
The exterior is a natural creamy off-white to grayish-cinnamon. While living specimens exhibit vibrant mantles (blues/greens), the cleaned shell is typically white. There are faint traces of yellowish-tan pigments near the growth lines. The interior (partially visible) appears smooth, porcelaneous, and bright white.
Rarity
Uncommon in the wild due to over-harvesting; Rare to find as a naturally washed-up beach specimen in this condition. It is a CITES-protected species.
Habitat
Marine; shallow tropical waters. Found in coral reefs and sandy substrates near reefs at depths of 2 to 20 meters, where sunlight can reach their symbiotic algae.
Geographic Range
Indo-Pacific region, spanning from the Red Sea and East Africa across to Polynesia, and from southern Japan down to northern Australia.
Description
An architectural marvel of the sea, this valve features 4 to 6 deeply folded longitudinal ribs. The most striking feature consists of the large, leaf-like 'flutes' or scales (scutes) that project outward from the ribs. The shell is remarkably thick and heavy for its size, with a deeply scalloped margin that would interlock perfectly with its opposing valve.
Key Features
Distinguished from other giant clams by the exceptionally large, well-spaced, and prominent leaf-like scales (flutes) across the entire surface of the ribs, and a relatively small byssal opening near the hinge.
Collector Value
Moderate ($40 - $150 USD depending on size and flute integrity). However, international trade is strictly regulated under CITES Appendix II, making legal specimens with proper provenance highly desirable and necessary for ethical collecting.
Condition Notes
Fair to Good. The primary structure is intact, but the delicate flutes show significant wear, chipping, and erosion typical of beach-worn or older handled specimens. Organic residue or 'dusting' is visible in the crevices. Collectibility Grade: Good (Collector-level for study, though not a 'Gem' specimen).
Interesting Facts
These clams are 'solar-powered'—they host symbiotic algae (zooxanthellae) in their mantle tissue that provide the clam with nutrients via photosynthesis. Historically, large valves were used as baptismal fonts in churches and as decorative basins.
Ecological Role
Acting as a natural reef filter and provider of calcium carbonate to the reef structure. They are currently listed as 'Conservation Dependent' or 'Vulnerable' in many regions due to aquarium trade demand and food harvesting.
Similar Species
Tridacna maxima (Small Giant Clam) has much smaller, more crowded scales; Tridacna gigas (True Giant Clam) is significantly larger and lacks the prominent leaf-like flutes.
Beach Finding Tips
Finding a complete, upright fluted clam on a beach is rare as the heavy shells sink or break in the surf. Look in lagoons or reef flats during extremely low tides in the Indo-Pacific, though harvesting live specimens is illegal in most regions.