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Sand bubbler crab Scopimera sp. Family Ocypodidae

Sand bubbler crabs are common on the sandy shores of Chek Jawa. They are not found on the sand bar. They are almost the same colour as sand, and as round as the sand balls they create. They bolt into their burrows at the slightest sign of danger. To observe them, stay still and avoid casting a shadow over them. Then look out for a moving ball of sand!

Sand patterns: Sand bubbler crabs are responsible for the delicate patterns of tiny balls on the sandy shores of Chek Jawa at low tide. They emerge as soon as the tide recedes. You can almost tell how long the tide has been out by the patterns of their sand balls. The more intricate the pattern of sand balls, the longer the tide has been out.

Sand bubbler parts: Sand bubbler crabs have eyes are on stalks that poke out of their round bodies. Their long pincers point downwards to scoop up sand into their mouths. The males may have larger pincers. Sand bubbler crabs have stiff hairs on their legs which they use to absorb water from the wet sand.

Sand bubbler Food: Sand bubbler 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. As they eat, a little path is scraped out on the sand from the burrow entrance. Little balls of sifted sand is piled up on either side of this path. As a result, there is often a 'path' among the piles of sand grains leading from the burrow entrance.

Role in the ecosystem: Sand bubbler 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.

quick facts
Body width to about 1.5cm, common on the sandy shore

Classification:
Order Decapoda
Class Malacostraca
Subphylum Crustacea
Phylum Arthropoda

See also ...
Other crabs of the Family Ocypodidae on Chek Jawa
Soldier crab (Dotilla myctiroides)
Fiddler crab (Uca sp.)

Links
Deposit feeders on Life on Australian Seashores by Keith Davey on the Marine Education Society of Australia website: Fact sheet on deposit feeders including the Sand bubbler crabs.

Other references

Barnes, Robert D. & Ruppert, Edward E., 1996. Invertebrate Zoology. Harcourt College Publishers. 6th Edition. pp. 1056, G-1-16, I-1-30.
Tan, Leo W. H. & Ng, Peter K. L., 1988. A Guide to Seashore Life. The Singapore Science Centre, Singapore. 160 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.
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