Tridacna squamosa in situ (Photo: Clay Bryce)
Tridacna squamosa in situ (Photo: Lisa Kirkendale)

Fluted Giant Clam

Tridacna squamosa

Shell  large (L30-40 cm), solid, inflated, slightly thin, semicircular and subequilateral. Moderate to small byssal gape. 5-6 broad well developed radial rib-like folds, same number of small ribs near postero-ventral margin. Strong, well-spaced flutes on folds. Exterior white, yellow, orange or pink, with interior often similarly coloured.

Morphology

Large heavy shell, but also delicate given extensive fluting.Lack of byssal attachment. Hypertrophied mantle that is brilliantly colored and extending beyond shell margin. Interior and exterior shell colors similar to T. crocea. Large siphons that are responsive to movement. Photosymbiotic.

Evolution

Tridacna crocea and T. squamosa are sister taxa (e.g. Huelsken et al. 2013, Herrera et al. 2015). There has been much intraspecific structure evident in T. crocea (e.g. DeBoer et al. 2008, Kochzius & Nuryanto 2008, Neo & Todd 2012, others). There has not been as much research on T. squamosa genetic structure, but what has been done has indicated less intraspecific variation than for T. crocea, a well-studied small giant clam species (e.g. Neo & Todd 2012, similar work in Thailand too). New work with larger geographic coverage has upturned this earlier understanding though and shown that T. squamosa is also highly structured, and more so than T. crocea in this study, with genetic endemism in the Red Sea populations (Hui et al. 2016).

Behaviour

Water jetting via large siphons in response to movement.

Method of reproduction

Broadcast spawner.

Habitat

Marine

Fluted giant clam is free-living as an adult and found on the bottom of reefal areas, including sandy areas, and often in lagoons from 1-4 m alive.

Distribution

QLD, NT and WA in Australia, but widely distributed in the Indo-west Pacific

Life Cycle

Hermaphroditic. Veliger larvae acquire photosymbionts from the environment.

Taxonomy

Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Heterodonta
Superorder: Imparidentia
Order: Cardiida
Superfamily: Cardioidea
Family: Cardiidae
Subfamily: Tridacninae
Genus: Tridacna
Species: squamosa
Name Published Year: 1819
Rank: species
Scientific Name Authorship: Lamarck
Commercial Impact: 

Aquarium trade, shell trade

Conservation Assessment: Least Concern

Net Conservation Benefits Fund

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Western Australian Museum Collections https://museum.wa.gov.au/online-collections/names/Tridacna-squamosa
Accessed 26 Apr 2025

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References

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