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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans > Superfamily Ocypodoidea > Genus Uca
Orange fiddler crab
Uca vocans
Family Ocypodidae
updated Oct 2016
Where seen? This tiny crab with a 'pimply' oversized pincer is commonly seen on our natural undisturbed shores, usually on softer, muddier areas more exposed to wave action than other fiddler crabs. This includes the bottom of swimming lagoons, shores near large boulders.

Features: Body width 2-3cm. Body squarish. The male fiddler crab's enlarged pincer almost twice as long as the body width. The enlarged pincer's outer palm is pimply with a large triangular depression. The movable upper finger meets (does not extend past) the immobile lower finger. The tips of the fingers are flattened and sword- or sabre-like. There is a wide gape between the upper and lower finger. The enlarged pincer's inner palm has a horizontal ridge of bumps. The immobile lower finger is orange or yellow. Body colours and patterns vary: some greenish, others greyish. Eyes greyish with dark tops, on long stalks greyish, walking legs short greyish to brown or orange.

Their burrows can be half a metre deep!

Sometimes mistaken for the Porcelain fiddler crab (Uca annulipes). More on how to tell apart the fiddler crabs commonly seen on our shores.


Pincer outside, pimply with triangular depression,
fingers flattened, sword-like.

Pulau Hantu, May 09
Horizongal ridge of bumps
on the inside of the pincer.

Pulau Ubin, May 08

From the back.
Chek Jawa, Oct 04

Female and male.
Pasir Ris, Jun 09

Females have two small pincers
Pulau Ubin, May 08


Pincer colours may vary.
Chek Jawa, Feb 02

Pulau Ubin, Feb 05

Different coloured backs.
Pulau Ubin, May 08


Males may be 'right' or 'left' handed.
Pulau Ubin, May 08

Tussel over a female?
Chek Jawa, Mar 11
 

Orange fiddler crabs on Singapore shores

Photos of Orange fiddler crabs for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map

Filmed on Pulau Ubin, May 08

Ubin - Fiddler crab run from SgBeachBum on Vimeo.



Links

References

  • Ng, Peter K. L. and Daniele Guinot and Peter J. F. Davie, 2008. Systema Brachyurorum: Part 1. An annotated checklist of extant Brachyuran crabs of the world. The Raffles Bulletin of Zoology. Supplement No. 17, 31 Jan 2008. 286 pp.
  • Lim, S., P. Ng, L. Tan, & W. Y. Chin, 1994. Rhythm of the Sea: The Life and Times of Labrador Beach. Division of Biology, School of Science, Nanyang Technological University & Department of Zoology, the National University of Singapore. 160 pp.
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