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| crabs text index | photo index |
| Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans |
| Elbow
crabs Family Parthenopidae updated Aug 10
Where seen? These tiny, slow-moving crabs look like bits of dirt or junk among seaweeds. Look very carefully to find them. Elbow crabs are commonly seen on our Northern shores, among seagrasses and seaweeds. Features: Body width 1-2cm. An obvious feature of the elbow crab (once you can actually see the crab) is its highly elongated pincers that stick way out from the sides of its body. The upper finger is moveable and curved towards the immobile lower finger. Males may have larger pincers than females. The thin walking legs are small and have pointed tips. Body somewhat triangular or pentangonal. The crab's body and claws may be fuzzy or bumpy and coloured the same as mud or sand. Some have fluffy algae or even tubeworms growing on the body and arms. The pincers are large, relative to the crab, and look like they can do some serious damage to small prey. The inner surface of the claws have a row of coloured bumps and spots that are probably used to startle predators. Elbow crab food: The elbow crab eats worms and small snails and clams. Role in the habitat: Elbow crabs are predators of small creatures. In turn, they are eaten by many animals higher up in the food chain. Some small species live on soft corals and sea urchins. Status and threats: Some of our elbow 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 also have an impact on local populations. |
 Pincers many times longer than its body. Changi, May 06  Bumps on the inner pincer. |
They are tiny well camouflaged crabs. That's why we should
avoid stepping areas thick with seaweeds and seagrasses.
Their 'elbows' are often much longer than their bodies!
 Pulau Sekudu, Jun 05 |
 Mama crab with egg mass on her abdomen. |
 Small eyes. |
Elbow crabs on Singapore shores
 Chek Jawa, Mar 03 |
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 Changi, Jul 07 |
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 Changi, Aug 09 |
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| Family
Parthenopidae recorded for Singapore from Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore 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.
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