learn only 3 things about them ...
These crabs have long pointy legs to cling to and scramble
They have a flat body to slip through narrow crevices.
are very shy and disappear at the slightest sign of trouble.
Where seen? Small grapsid crabs
are commonly seen on many of our rocky shores and mangroves, especially
at night. They are among the colourful crabs you might see even at
high tide. But they are more active at night and fast moving. During
the day, you will rarely see more than a purplish hairy leg peeking
out from a crevice! The larger species are sometimes seen on the offshore
Features: Body width 4-6cm. Grapsid
crabs are adapted for scrambling over rocks and other slippery surfaces.
Many can stay out of the water for some time. Grapsid crabs are also
sometimes called Shore crabs. They have well-developed hooks on the
tips of their long legs that grip these surfaces. Their bodies and
legs are flattened, allowing them to squeeze deep into narrow cracks
and crevices. In some species, males have larger pincers than females.
The Tuberculated Sally-light-foot
crab (Plagusia squamosa) is sometimes mistaken for a grapsid
crab. But it belongs to another family.
What do they eat? Grapsid crabs
are scavengers and will eat almost anything. They also eat seaweed.
Grapsidae recorded for Singapore
Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity
**Ng, Peter K. L. & N. Sivasothi, 1999. A Guide
to the Mangroves of Singapore II (Animal Diversity).
***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.
in red are those listed among the threatened
animals of Singapore from Ng, P. K. L. & Y. C. Wee, 1994. The
Singapore Red Data Book: Threatened Plants and Animals of Singapore
- 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.
- Wee Y.C.
and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore.
National Council on the Environment. 163pp.
- Ng, P. K.
L. & Y. C. Wee, 1994. The
Singapore Red Data Book: Threatened Plants and Animals of Singapore.
The Nature Society (Singapore), Singapore. 343 pp.
- Jones Diana
S. and Gary J. Morgan, 2002. A Field Guide to Crustaceans of
Australian Waters. Reed New Holland. 224 pp.