Fluted Giant Clam (also known as the Scaly Clam or Small Giant Clam)
Phylum: Mollusca; Class: Bivalvia; Order: Cardiida; Family: Tridacnidae; Genus: Tridacna; Species: Tridacna squamosa · Tridacnidae (Giant Clam family) or Cardiidae (Cockle family subfamily Tridacninae) · Bivalve (two-shelled); this specimen is a single valve. Shape: Fan-like/Fluted.
Species
Tridacna squamosa (Confidence Level: 95%)
Shell Type
Bivalve (two-shelled); this specimen is a single valve. Shape: Fan-like/Fluted.
Family
Tridacnidae (Giant Clam family) or Cardiidae (Cockle family subfamily Tridacninae)
Size
Approximately 10-12 inches (25-30 cm) in length. This is a mid-sized adult, as the species typically reaches up to 16 inches (40 cm).
Color & Pattern
Off-white to creamy beige exterior, likely sun-bleached. The interior (visible in similar specimens) is typically pure white and porcelaneous. The natural state often features subtle yellow or orange tinges near the scales. The top shell in the image shows distinct maroon/red spotting patterns characteristic of Hippopus hippopus, but the primary subject is monochrome due to weathering.
Rarity
Uncommon in the wild due to over-harvesting; Rare as a beach find in pristine condition. Legally, they are highly regulated under CITES.
Habitat
Shallow tropical marine waters, typically attached to coral reefs or sandy substrates near reefs at depths of 1 to 20 meters. They rely on sunlight for their symbiotic algae.
Geographic Range
Indo-Pacific region, ranging from the Red Sea and East Africa across to the Marshall Islands and Polynesia, and from southern Japan to northern Australia.
Description
A heavy, thick-walled bivalve characterized by 4 to 6 large, deeply convex primary radial ribs. The most striking feature is the presence of prominent, leaf-like 'flutes' or scales (scutes) that project from the ribs, representing past growth stages. The valve margin is deeply undulating and fits into its opposite mate with a zig-zag interlocking pattern.
Key Features
Large, spaced-out leaf-like scales (scutes) on the radial ribs; relatively symmetrical fan shape; a small byssal opening (compared to Tridacna maxima).
Collector Value
Moderate ($40 - $120 USD depending on size and flute preservation). Valuable to collectors for their architectural beauty. Note: International trade requires CITES permits, making legally sourced, high-quality specimens more desirable.
Condition Notes
Fair to Good. The shell shows significant weathering and calcification, suggesting it was exposed to the elements or buried in sand for some time. The delicate 'flutes' are partially eroded or chipped, which is common in older, beach-worn specimens. Collectibility Grade: Good.
Interesting Facts
Tridacna squamosa hosts zooxanthellae (symbiotic algae) in its colorful mantle tissue, which provide the clam with nutrients via photosynthesis. Culturally, these shells were used in the South Pacific as bowls or building materials. Today, they are protected under CITES Appendix II to prevent extinction due to the aquarium trade and food demand.
Ecological Role
These clams act as 'nurseries' for small fish and invertebrates on the reef. They are primary producers due to their symbiosis and help filter sea water. They are currently threatened by ocean acidification and over-harvesting.
Similar Species
Tridacna maxima (Small Giant Clam) which has a more elongated shape and much smaller, tighter scales; and Tridacna gigas, which lacks the prominent leaf-like flutes and grows significantly larger.
Beach Finding Tips
Look for these in Indo-Pacific areas after heavy storms or in areas with fossilized reef uplift. However, it is illegal to remove them from many national parks and international travel with them is restricted without permits.