Cook Islands Biodiversity & Natural Heritage

Uca crassipes

Kō‘iti Raukura

a fiddler-crab

Multimedia & Additional Resources

Type Description Download
Open this image in pop-up window Image: Male - two views 51KB
Open this image in pop-up window Image: Males in combat 44KB
Open this image in pop-up window Image: Male on chimney built by female 52KB

General Information

COMMON NAMES: a fiddler-crab, Mangrove Fiddler Crab

TRADITIONAL NAMES: Kō‘iti Raukura (RR), Koro‘iti (AK)

GLOBAL DISTRIBUTION: NATIVE se.Asia - w.Pacific - Cooks - Tuamotu - Marquesas

COOK ISLANDS STATUS: Native; S.Group - common; N.Group - absent?; Marine, near-shore; mud-flats, especially near stream-outlets

SIGNIFICANCE LIST: oil production;

KEY FEATURES: Carapace 13x20mm (LxW), and fiddle to 34mm long. CARAPACE wide between the eyes (a "wide-fronted fiddler-crab"). COLOUR dark blue w/wo a few large pale blotches. MALE "fiddle" (=chela or cheliped) scarlet to red-orange base with paler fingers; a sharp-edged short-triangular depression at base of the fixed-finger (=pollex).

SIMILAR SPECIES: See under Uca tetragonon.

Enlarged Image of 'Uca crassipes'

Cook Islands Distribution

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Southern Group: Present    Makatea:

Northern Group: -

Key to Symbols

Scientific Taxonomy

Uca crassipes (Adams & White, 1848)
SYNONYMS: Gelasimus crassipes; Uca crassipes; Uca gaimardi; Uca latreillei; Uca splendidus; Uca chlorophthalmus crassipes [In the subspecies system U. c. chlorophthalmus is from e.Africa and throughout Indian Ocean; U. c. crassipes is from Malaysia and the Pacific to the Tuamotu.]

TAXONOMY: ANIMALIA; ARTHROPODA; CRUSTACEA; MALACOSTRACA; EUMALACOSTRACA; Eucarida; Decapoda; Reptantia; Brachyura; Brachygnatha; Brachyrhyncha; OCYPODIDAE

More Information

GENERAL NOTE: Uca crassipes, like other fiddlers, feed outside their burrows when the tide uncovers the substrate during daylight hours. Waving displays, combat, and courtship usually occur for 2 or 3 days of around Spring Tide. The large females usually build chimneys at this time and males approach the chimneys (sometimes waving). After courtship mating occurs on the ground, on the chimney or in the burrow. Male combat is ritualised and does not involve injury.

Vouchers & References

Cooks: 042. Aitutaki: field-specimen, NBSAP School, 12/2000, ID GM.

Special Reference: Forest & Guinot 1961 [Fr.]

Data Update History (information):
zTX, zB02, zM02, zupM06a, zD02, zupD06a

Web Resources

Citation Information

McCormack, Gerald (2007) Cook Islands Biodiversity Database, Version 2007.2. Cook Islands Natural Heritage Trust, Rarotonga. Online at Copy citation to system clipboard
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