learn only 3 things about them ...
These crabs have long legs with pointy tips to cling to
and scramble over hard surfaces.
They have a flat body to slip through narrow crevices.
are very shy and disappear at the slightest sign of trouble.
Where seen? Small sesarmid crabs
are commonly seen in our mangroves, especially at night. There are
as many as 40 species of these crabs in our mangroves. They are often
hard to spot as they are well camouflaged, although some may have
colourful markings. They are more active at night.
Features: Body width 4-6cm. Sesarmid
crabs are adapted for scrambling over slippery surfaces. 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. Many can stay out of the water for some
Role in the habitat: By feeding
on mangrove leaves, these crabs recycle nutrients in the mangrove
forest. Quickly breaking down the leaves for others in the food chain
to eat, e.g., animals that eat the fragments left over by the crabs,
what comes out of the crab after it eats the leaves, and of course,
the crab itself!
Status and threats: Some of our
Sesarmid crabs are listed among the threatened animals of Singapore.
Like other creatures of the intertidal zone, they are affected by
human activities such as reclamation and pollution. Trampling by careless
visitors can also affect local populations.
About to munch on flowers?
Sungei Buloh Wetland Reserve, Sep 03
This mama tree-climbing crab
was carrying lots of eggs!
Kranji, Jun 06
crabs on Singapore shores
Sesarmidae 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 Davison, G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008.
The Singapore Red Data Book: Threatened plants and animals of Singapore.
Family Sesarmidae (previously Grapsidae)
Episesarma sp. (Tree
Episesarma chentongensis (Pink-fingered tree climbing crab)
Episesarma singaporensis (Singapore tree climbing crab)
Episesarma versicolor (Violet tree climbing crab)
**Nanosesarma (Beanium) batavicum
**Nanosesarma (Beanium) edamensis
**Nanosesarma (Beanium) nunongi
Nanosesarma spp. (Dwarf sesarmine crabs)
Perisesarma/Chiromantes eumolpe (Face-banded
Perisesarma indiarum (Face-banded
Geosesarma nemesis (EN:
Geosesarma peraccae (VU: Vulnerable)
Haberma nanum (VU:
(Mound crab) (EN: Endangered)
Selatium brocki (Mangrove tree-dwelling
- 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. (Online
PDF on the Raffles Bulletin of Zoology website).
- 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.
G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore
Red Data Book: Threatened plants and animals of Singapore.
Nature Society (Singapore). 285 pp.
- Jones Diana
S. and Gary J. Morgan, 2002. A Field Guide to Crustaceans of
Australian Waters. Reed New Holland. 224 pp.