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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans > Family Portunidae
Mottled swimming crab
Thalamita sp.*
Family Portunidae
updated Dec 2019
Where seen? This well camouflaged swimming crab seen on some of our shores on coral rubble and reefs. It is particularly active at night.

Features: Body width 4-5cm. Body rectangular, sides of the body with 5 dark blue-light blue-brown tipped spines, the fourth spine is tinier than the others.The eyes are very wide apart, between the eyes are 4-6 rounded lobes. Last pair of legs are paddle-shaped. Body has fine hairs that trap sediments, colour mottled greenish, brown, bluish. The edge of the body and segments on the body upper surface has a fine blue-brown banded pattern.

Pulau Semakau, Nov 09

4 lobes between the eyes.
Fine banded pattern on body edge
and body upper surface.

5 spines on the side of the body.
Fourth spine smaller than other spines.

Sometimes 6 lobes betweeen the eyes.

Fourth spine smaller than other spines.

Pulau Senang, Jun 10

About to mate?
Terumbu Pempang Laut, Aug 10

*Species are difficult to positively identify without close examination.
On this website, they are grouped by external features for convenience of display.

Mottled swimming crabs on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Punggol, Sep 18
Photo by Dayna Cheah on facebook.

Sentosa Serapong, May 12
Photo shared by Marcus Ng on flickr..

Berlayar Creek, Oct 17
Photo by Marcus Ng on facebook.

Terumbu Pempang Tengah, Jun 20
Photo by Jonathan Tan on facebook.

Sisters Islands, May 07
Photo shared by Marcus Ng on facebook.

  Links References
  • 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.
  • 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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