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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans > Family Grapsidae
Sally-light-foot crab
Grapsus albolineatus
Family Grapsidae
updated Oct 2016

Where seen? This colourful and swift crab is sometimes seen on our some of our rocky shores. Small groups may clamber noisily among rocks on seawalls or natural rocks. Sometimes, it may also be seen on the reef flats near the rocky shore. It is more active at night and seldom seen during daylight. Very shy, it disappears instantly into crevices at the slightest sign of danger. Or it may flatten against the encrusted rocks, where it blends in with this surroundings.

Features: Body width 5-6cm. Body circular flat, dark with a pattern of light spots in bands at the lower portion of the body. Pincers very short flattened. Very long walking legs tipped with pointy claws. With these legs, the crab clings tightly so it doesn't get washed away in the waves, and can scramble quickly among slippery rocks. Colours seen range from reddish to bluish and greenish. 'Alba' means 'white' and 'lineatus' means lines. The body indeed has fine white lines. Males have larger pincers than the females.

Sometimes mistaken with the Scaly rock crab (Plagusia squamosa) which has a more squarish less flat more bumpy body.

What does it eat? It is a scavenger and also eats seaweeds. It has relatively small pincers that work like scissors to snip and scrape off edible titbits.

Kusu Island, Apr 05

East Coast, May 11

Moult at top left corner, crab in bottom right.
Sisters Islands, Jan 06

A moulted crab (blue) with moult (orange).
Sisters Islands, Jul 04

Flattened against an encrusted surface.
Kusu Island, Sep 10

Sally-light-foot crabs on Singapore shores

Photos of Sally-light-foot crabs for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map


Tanah Merah, Jun 09
Photo shared by James Koh on his flickr.


East Coast, Jun 07

Photo shared by Loh Kok Sheng on his blog.

East Coast PCN, Apr 17

Photo shared by Loh Kok Sheng on facebook.

East Coast, Marina Bay, Oct 15

Photo shared by Loh Kok Sheng on flickr


Terumbu Buran, Nov 10
Photo shared by Loh Kok Sheng on his blog.

St. John's Island, Sep 09
Photo shared by Neo Mei Lin on her blog.

Pulau Tekukor, Aug 17
Photo shared by Richard Kuah on facebook.

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.
  • Jones Diana S. and Gary J. Morgan, 2002. A Field Guide to Crustaceans of Australian Waters. Reed New Holland. 224 pp.
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