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Tridacna maxima

Pa‘ua

Small Giant-Clam

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General Information

COMMON NAMES: Small Giant-Clam, Elongate Giant-Clam, Burrowing Giant-Clam, Rugose Giant-clam

TRADITIONAL NAMES: Pa‘ua (RR), Pā‘ua (MG MT AK), Paua (AT), Pā‘uā (MK), Pāsua (TS TW), Pāyua (PK NS); COMMENT: Pa‘ua / Pahua is the traditional name for the giant clam and commonly harvested species is Tridacna maxima. The uncommon Fluted Giant-Clam is sometimes distinguished by a species-specific name.

GLOBAL DISTRIBUTION: NATIVE e.Africa - Pitcairns; n. to s.Japan; s. to New Caledonia

COOK ISLANDS STATUS: Native; S.Group - common; N.Group - common; Marine, near-shore

SIGNIFICANCE LIST: ; RedList, Globally and Nationally endangeredFood, Medicine

KEY FEATURES: Large, rugged shell, to 25cmL (max.35cm). VALVES similar, inflated, oval; joint (=umbones) at anterior 30%; ventral opening (=byssal orifice) large, with 4-9 small, non-interlocking ridges; surface with 6-7 wide, convex radial-ridges with erect, low, concentric scales (=scutes). Inhalant siphon with fringing tentacles. COLOUR external greyish white; interior glossy white. EXPOSED MANTLE variable, brightly coloured. POSITION partially buried into corals.

SIMILAR SPECIES: Fluted Giant-clam (Tridacna squamosa) has radial ridges with erect, high, blade-like scales (vs. erect, low, concentric scales); joint is near centre (vs. anterior 30%).

Cook Islands Distribution

View Distribution Map

Southern Group: Present Makatea:
RR	MG	AT	MK	MT	AK	PL	TK	MN
	^P	^P	^P		^+++

Northern Group: Present
TN	MH	RK	PK	NS	SW
			++

Key to Symbols

blank	no data
-	absent	L	localised
X	extinct 'naturally'	W	widespread
XQi	quarantine intercepted	R	recent
XQe	eradicated	?	query preceding category
P	present	T?	taxonomic query
S	seasonal	nn	present, said to have no name
O	occasional	?1	present, name not investigated
++++	very common	?2	presence not verified, no name recorded
+++	common	N/A	absent, name not expected
++	uncommon
+	rare
Cook Islands islands: RR =Rarotonga, MG = Mangaia, AT =‘Ātiu, MK=Ma‘uke, MT=Miti‘āro, AK=Aitutaki, PL=Palmerston, PN=Penrhyn, MN=Manuae, TK=Takūtea, TN=Tongareva (TS=Tongaleva Spoken, TW=Tongareva Written, they say "el" but write "r"), MH=Manihiki, RK=Rakahanga, PK=Pukapuka, NS=Nassau, SW=Suwarrow. After a Polynesian name: ^=orthography query. Countries and other: FIJ=Fiji, WT=Wallis & Futuna, SAM=Samoa, TON=Tonga, NIU=Niue, CK=Cook Islands, CKM=Cook Islands Māori, FP=French Polynesia, AUS=Australs, SOC=Societies, TAH=Tahiti, TUA=Tuamotus, MQS=Marquesas, MNG=Mangareva, PIT=Pitcain group, EAS=Easter Island, HAW=Hawai‘i, NZ=New Zealand, NZM=New Zealand Māori

Scientific Taxonomy

Tridacna maxima (Röding, 1798)
SYNONYMS: Tridacna (Chametrachea) maxima Röding, 1798

TAXONOMY: ANIMALIA; MOLLUSCA; PELECYPODA (Bivalvia); LAMELLIBRANCHIA; Heterodonta; TRIDACNIDAE

More Information

SIGNIFICANCE NOTES -
BIODIVERSITY: RedList, Globally and Nationally endangered. Comment: On RedList as LR/cd (Lower Risk, Conservation Dependent), and Insufficiently Known. There is concern about this species although it is not listed as Critically Endangered, Endangered or Vulnerable. (RedList 2005)
POSITIVE SIGNIFICANCE: Food, Medicine. Comments: Cites listed

Vouchers & References

Vouchers:
Cooks: Morgan 795-797. Mangaia: specimen, College, 9/2000, ID GMcC. Atiu: field-specimen, College collection, 10/2000, ID GMcC. Mauke: field-specimen, College collection, 3/2001, ID GMcC. Aitutaki: fieldspecimen, NBSAP School, 12/2000, ID GM. Pukapuka: fieldspecimen, 2/2004, G.McCormack with ID as Tridacna maxima.

References:
None recorded.

Data Update History (information):
zTX, zB02, zM02, zupM06a, zD06a

Web Resources

Citation Information

McCormack, Gerald (2007) Cook Islands Biodiversity Database, Version 2007.2. Cook Islands Natural Heritage Trust, Rarotonga. Online at http://cookislands.bishopmuseum.org.
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