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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans > Family Xanthidae
Floral egg crab
Atergatis floridus

Family Xanthidae
updated Dec 12
if you learn only 3 things about them ...
These 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 round well-camouflaged crab is commonly seen on our Southern shores, among coral rubble or reefs. But it is usually not as numerous as the Red egg crab (Atergatis integeriimus). It is more active at night. 'Floridus' in Latin means 'flowery'.

Features: Body width 8-10cm.Body oval, smooth surface and smooth body edge. Greenish- and greenish-blue-brown always with a fine network of fine lines white or yellow that forms a delicate lacy floral pattern. Also called the Shawl crab because the lacy white pattern resembles a shawl. Large pincers both about equal in size, smooth (no pimples) with black tips that are spoon-shaped. Males may have larger pincers. Walking legs thick squarish with lilac edges, not hairy. Like most other Xanthid crabs, it is highly poisonous and should not be eaten.

What does it eat? Although it is described as a vegetarian, one was seen happily eating a fish. Like other Xanthid crabs, it is poisonous and should not be eaten.

Status and threats: This crab is listed as 'Vulnerable' on the Red List of threatened animals of Singapore.

Sentosa, May 04
 

A pair of mating egg crabs.
Cyrene Reef, Jul 10
Photo shared by James Koh on his blog.

Eating a Brown-stripe wrasse.
Sentosa, Sep 04

Floral egg crabs on Singapore shores

Photos of Floral egg crabs for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map


Terumbu Pempang Tengah, May 11
Photo shared by Loh Kok Sheng on his blog.

Terumbu Bemban, Jun 10
Photo shared by Toh Chay Hoom on her blog.

Beting Bemban Besar, May 10
Photo shared by James Koh on his blog.


Pulau Pawai, Dec 09
Photo shared by Loh Kok Sheng on his flickr.

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

Pulau Jong, Apr 15
Photo shared by Marcus Ng on facebook.


Pulau Senang, Jun 10

Pulau Senang, Aug 10

Pulau Salu, Aug 10

Links References
  • Peter K. L. Ng and Peter J. F. Davie, 31 Dec 2007, On the identity of Atergatis floridus (Linnaeus, 1767) and recognition of Atergatis ocyroe (Herbst, 1901) as a valid species from the Indian Ocean (Crustacea: Brachyura: Xanthidae) The Raffles Bulletin of Zoology 2007 Supplement No. 16 : 169-175 National University of Singapore
  • 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.
  • Gopalakrishnakone P., 1990. A Colour Guide to Dangerous Animals. Venom & Toxin Research Group, Faculty of Medicine, National University of Singapore. 156 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.
  • Chuang, S. H., 1961. On Malayan Shores. Muwu Shosa, Singapore. 225 pp., plates 1-112.
  • 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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