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Soldier crab Dotilla myctiroides Family Ocypodidae

Soldier crabs are common on the sand bar. They are not found on the sandy shore. Their burrows are marked by the rather large balls of sand around the entrance. To spot these crabs, you will have to wait quietly next to their burrows. In a few minutes, they will appear. If you stay still, they will go about their amusing business.

Squadron of soldiers? Soldier crabs got their common name because elsewhere, they troop about in large groups at low tide. Those on Chek Jawa, however, don't do this.

Soldier crab parts: Soldier crabs look quite comical with their spherical bodies, eyes on stalks, and long, downward pointing pincers. Soldier crabs are well adapted for life out of water and are among the few marine creatures that roam the sand bar at low tide. They can absorb air through special parts of their legs which are thinner. They also absorb water from the sand through silky hairs on their abdomen. Unlike most crabs, Soldier crabs can run forwards as well as sideways. And they can move very fast indeed!

Soldier food: Soldier crabs eat the thin coating of detritus on sand grains. They scrape up sand grains with their downward pointing pincers and bring these to their mouthparts that then sift out any tiny food particles. The shifted sand is then discarded in a little ball. They leave larger sand balls in untidy heaps, unlike the more tidy Sand bubbler crabs.

Role in the ecosystem: Soldier crabs are eaten by many animals higher up in the food chain. Shorebirds, for example, snack on them for sustenance to make their long migratory journeys.

Status and threats: The Soldier crab (Dotilla myctiroides) is listed among the threatened animals of Singapore due to loss of our natural beaches. While somewhat common on Chek Jawa, they are not easily seen elsewhere in Singapore.

quick facts
Body width to about 1.5cm, common on the sand bar especially the northern arm of the sand bar

Classification:
Order Decapoda
Class Malacostraca
Subphylum Crustacea
Phylum Arthropoda

See also ...
Other crabs of the Family Ocypodidae on Chek Jawa
Sand bubbler crab (Scopimera sp.)
Fiddler crab (Uca sp.)

Links

Family Ocypodidae by Stefano Cannicci on the East African Mangroves site of the Natural History Museum of Florence: facts and photos on ghost crabs, fiddler crabs and soldier crabs.

Other references

Tan, Leo W. H. & Ng, Peter K. L., 1988. A Guide to Seashore Life. The Singapore Science Centre, Singapore. 160 pp. online version
Ng, Peter K. L. & N. Sivasothi, 1999. A Guide to the Mangroves of Singapore II (Animal Diversity). Singapore Science Centre. 168 pp. online version
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.
Chuang, S. H., 1961. On Malayan Shores. Muwu Shosa, Singapore.225 pp., plates 1-112.
Davey, Keith, 1998. A Photographic Guide to Seashore Life of Australia. New Holland, Australia.144 pp.

a companion website to the chek jawa guidebook website©ria tan 2003 www.wildsingapore.com

a companion website to the chek jawa guidebook
website©ria tan 2003 www.wildsingapore.com