Crocus giant clam (Tridacna crocea)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Mollusca · Class: Bivalvia · Order: Cardiida · Family: Cardiidae · Genus: Tridacna.

Accepted name: Tridacna crocea · Authority: Lamarck, 1819 · Taxonomic status: accepted · AphiaID: 207673.

Synonyms and superseded combinations recorded for this taxon: Tridacna (Chametrachea) crocea Lamarck, 1819; Tridacna cumingii Reeve, 1862; Tridacna ferruginea Reeve, 1862.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=207673 (CC BY 4.0). Accessed 2026-09-25.

Biology and life history (SeaLifeBase)

Measured values published by SeaLifeBase for Tridacna crocea. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 15 cm · Common length: 11 cm · Depth range: 0–20 m · Habitat zone: benthic · Vulnerability index: 10 of 100 · Fishery importance: commercial · Aquarium trade: never/rarely.

SeaLifeBase notes: Found in intertidal areas on corals (Ref. 75831).

Source: SeaLifeBase species summary (SpecCode 84545) — https://www.sealifebase.se/summary/Tridacna-crocea.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-25.

Distribution and occurrence records (GBIF)

6,146 georeferenced occurrence records for Tridacna crocea are published through GBIF from 35 countries or marine areas. The map above plots 236 distinct locations from a sample of 3,000 records, omitting 31 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: Indonesia (1,275); New Caledonia (1,251); Australia (860); Palau (848); Papua New Guinea (366).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 4372638) — https://www.gbif.org/occurrence/search?taxon_key=4372638&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=207673 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-25.

Conservation status (IUCN Red List)

The IUCN Red List assesses Tridacna crocea Lamarck, 1819 as Least Concern (code LC). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.

Source: IUCN Red List of Threatened Species (taxon 22135) — https://www.iucnredlist.org/species/22135/0; GBIF IUCN Red List category endpoint (taxonKey 4372638) — https://api.gbif.org/v1/species/4372638/iucnRedListCategory. Accessed 2026-09-25.

Description and natural history (Wikipedia)

The boring clam is the smallest clam in the subfamily Tridacninae and grows to a maximum shell size of 15 cm. It has two, thick valves joined by a hinge which is typically between a third and less than a half of the width of the shell. Typically shells are slightly to moderately elongate, and the animal is strongly inflated, especially near the hinge. The upper valve has six to ten flattish folds which interlock at the margin with similar folds on the lower valve so that they can clamp together and the shell can close tightly.

The lower valve has slits through which the byssal threads emerge which secure the animal to the seabed. This clam burrows into the substrate and this process tends to wear away the outer surface of the valves and smooth them off. They also may become distorted by burrowing into substrates of uneven hardness.

The colour of the valves is generally greyish-white, sometimes with a hint of pink-orange, yellow or orange colour -this colouration can form a band near the top margin, especially on the interior surface. The mantle, the soft body wall which covers the animal's internal organs, projects from between the valves when they are open and is brightly coloured.

It can be various shades of blue, green, purple, gold, orange or brown, often patterned with spots, stripes or squiggles. It has many small protrusions on the exposed surface and a line of simple eyes near the margin. The inhalent siphon, through which water is drawn into the shell, is surrounded by many small tentacles and the exhalent siphon is often long and tubular.

Distribution and habitat

The boring clam is native to the Indo-Pacific. Its range extends from Malaysia, Vietnam and Japan to Indonesia, the Philippines, Palau, New Guinea, Australia, the Solomon Islands and Vanuatu. At one time it was known from Guam and the Northern Mariana Islands but it may now be locally extinct in these locations. Its typical habitat is embedded in massive corals.

Source: Wikipedia: Tridacna crocea — https://en.wikipedia.org/wiki/Tridacna_crocea (CC BY-SA 4.0). Accessed 2026-09-25.