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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans
Sesarmid crabs
Family Sesarmidae
updated Dec 2019

if you 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.
They 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 time.

About to munch on flowers?
Sungei Buloh Wetland Reserve, Sep 03

This mama crab was carrying lots of eggs!
Kranji, Jun 06
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.

Some Sesarmid crabs on Singapore shores


Family Sesarmidae recorded for Singapore
from Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore
+from The Biodiversity of Singapore, Lee Kong Chian Natural History Museum.
**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.
^from WORMS

  Family Sesarmidae (previously Grapsidae)
  Bresedium sedilense

Clistocoeloma lanatum
Clistocoeloma merguiense

+Clistocoeloma villosum

Episesarma sp. tree climbing crabs with list of species recorded for Singapore

+Fasciarma fasciatum

Geosesarma clavicrure
Geosesarma nemesis
(EN: Endangered)
Geosesarma peraccae
(VU: Vulnerable)

Haberma nanum
(VU: Vulnerable)

Labuanium politum

+Lithoselatium kusu
(Kusu rock crab)

spp. (Dwarf sesarmine crabs)
^Nanosesarma (Beanium) batavicum=^Nanosesarma batavicum
^Nanosesarma (Beanium) edamensis=^Nanosesarma edamense
Nanosesarma minutum
^Nanosesarma (Beanium) nunongi=^Nanosesarma nunongi
Nanosesarma pontianacense

Neosesarma gemmiferum

Nanosesarmatium smithi=^Neosarmatium smithi

+Parasesarma eumolpe
+Parasesarma rutilimanum

Perisesarma bidens
Perisesarma dussumieri
Perisesarma/Chiromantes eumolpe=^Perisesarma eumolpe
(Face-banded sesarmine crabs)
+Perisesarma fasciatum
Perisesarma indiarum
(Face-banded sesarmine crabs)
+Perisesarma cf. lenzii
Perisesarma onychophorum
Perisesarma semperi

+Pseudosesarma bocourti
+Pseudosesarma edwardsi

*Sarmatium germaini (Mound crab) (EN: Endangered)
Sarmatium striaticarpus

Selatium brockii
(Mangrove tree-dwelling crabs)

Sesarmoides borneensis (EN: Endangered)

Links References
  • 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.
  • 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. 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.
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