updated Oct 2016
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 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).
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
climbing crabs with list of species recorded for
Geosesarma nemesis (EN:
Geosesarma peraccae (VU: Vulnerable)
Haberma nanum (VU:
+Lithoselatium kusu (Kusu rock crab)
Nanosesarma spp. (Dwarf sesarmine crabs)
^Nanosesarma (Beanium) batavicum=^Nanosesarma batavicum
^Nanosesarma (Beanium) edamensis=^Nanosesarma edamense
^Nanosesarma (Beanium) nunongi=^Nanosesarma nunongi
Nanosesarmatium smithi=^Neosarmatium smithi
Perisesarma/Chiromantes eumolpe=^Perisesarma eumolpe (Face-banded
Perisesarma indiarum (Face-banded
germaini (Mound crab) (EN:
Selatium brockii (Mangrove tree-dwelling
- Marcus F. C. Ng. 28 Oct 2016. A mangrove crab Perisesarma fasciatum at Pulau Ubin. Singapore Biodiversity Records 2016: 156
- Tan Heok Hui. 5 December 2014. Kusu rock crabs at Pulau Senang, Lithoselatium kusu. Singapore Biodiversity Records 2014: 320.
- 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.