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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans > Family Xanthidae
Red egg crab
Atergatis integerrimus

Family Xanthidae
updated Oct 2016
if you learn only 3 things about them ...
These colourful crabs are poisonous to eat! Their toxins are NOT destroyed by cooking.
They are generally secretive and slow-moving.
They are not venomous but it's best not to touch them.

Where seen? This colourful round crab can be very commonly seen on many of our shores in coral rubble areas and reefs. Slow moving, it usually hides under large coral rubble pieces, but can be quite active at night.

Features: Body width 8-10cm. Large oval somewhat egg-shaped body with a smooth edge (not 'toothed'). Reddish brown, orangey to bright red, usually with scattered white spots. Juveniles have a white margin around the body. Large pincers both about equal in size, smooth (no pimples) with black tips that are spoon-shaped. Males may have larger pincers. Walking legs not hairy. Juveniles are light brown with a white band around the edge of the body. Like most other Xanthid crabs, it is highly poisonous and should not be eaten.

Sometimes mistaken for stone crabs (Myomenippe hardwicki). Stone crabs look similar but have green eyes ringed with red. Stone crabs are usually plain (no dots) and tend to be grey or beige but may sometimes be reddish. More about how to tell apart crabs with big pincers.

Status and threats: This crab is listed as 'Vulnerable' in the Red Data list of threatened animals of Singapore.

Raffles Lighthouse, Aug 06

Small eyes which are all red.
Tiny white spots on the body.

A juvenile Red egg crab.
Tuas, Nov 03

A pair of mating egg crabs.
Sentosa, Aug 06

Pincers with spoon-shaped tips
and large bumps.

Eating a White sea urchin.
Tanah Merah, Jun 09

Manipulating an algae covered stone.
Labrador, May 06

With one white leg.
Terumbu Pempang Tengah, May 11

Red egg crabs on Singapore shores

Photos of Red egg crabs for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map


Tanah Merah, Jun 10
Photo shared by Loh Kok Sheng on his flickr.

Seringat-Kias, Aug 12
Photo shared by Loh Kok Sheng on his blog.

Terumbu Buran, Jan 10
Photo shared by Loh Kok Sheng on flickr.


South Cyrene, Oct 10
Photo shared by Loh Kok Sheng on flickr.

Terumbu Pempang Laut, Apr 11
Photo shared by Russel Low on facebook.

Pulau Senang, Aug 10


Pulau Biola, Dec 09
Photo shared by James Koh on his flickr.

Pulau Pawai, Dec 09

Pulau Sudong, Dec 09


Terumbu Berkas, Jan 10

Terumbu Salu, Jan 10
Photo shared by Loh Kok Sheng on his flickr.

Pulau Senang, Jun 10

Acknowledgements
Grateful thanks to Ondřej Radosta and Ryanskiy Andrey from ID Plase (Marine Creatures) facebook page for helping me to understand the appearance of juvenile Atergatis integerrimus.

Links

References
  • Eugene Goh, Jerome Yong, Brian Cabrera, Ron Kirby Manit & Karenne Tun. 6 November 2015. Red egg crab releasing larvae. Singapore Biodiversity Records 2015: 171-172
  • Chou, L. M., 1998. A Guide to the Coral Reef Life of Singapore. Singapore Science Centre. 128 pages.
  • 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.
  • 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.
  • Gopalakrishnakone P., 1990. A Colour Guide to Dangerous Animals. Venom & Toxin Research Group, Faculty of Medicine, National University of Singapore. 156 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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