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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans > Superfamily Majoidea
Velcro crab
Camposcia retusa
Family Inachidae
updated Dec 2019
if you learn only 3 things about them ...
They attach living sponges and seaweeds as a disguise.
The disguise continues to grow and other animals live on it.
They tend to move slowly.

Where seen? This superbly disguised crab is commonly encountered on our Northern shores, on coral rubble and seagrasse areas. But it requires a keen eye to spot!

Features: Body width 3-6cm. Body tear-drop shaped, without large spines on the sides. Often all you can see are its tiny eyes on long curved eyestalks at the tip of its pointed head. Pincers short cylindrical, claws slender and curving.

Upperside
Chek Jawa, Aug 05

Underside.

Pincers are undecorated.
This crab snips off bits of sponges and seaweed or selects suitable shells and debris. These are then stuck firmly onto the fine, hooked hairs which densely cover its body and legs and thus act like the 'velcro' after which it is named. Some seem to stick on a protruding 'head gear' on their heads.

These 'decorations' not only camouflage the crab, but the distasteful nature of some sponges might also give predators second thoughts about taking a bite out of the crab.
The attached sponges and algae often continue to grow. Tiny animals might settle on the sponges.

What does it eat? Relying on its disguise, the crab moves slowly, feeding on small creatures. Its dainty narrow feeding pincers are often the only parts of its body left unadorned.

Status and threats:
This crab is listed as 'Vulnerable' on the Red List of threatened animals of Singapore. It is popular in the aquarium trade and the Singapore Red Data Book states that its collection from Singapore should be controlled or stopped.

Pulau Sekudu, Jul 08

Chek Jawa, Jul 03

Chek Jawa, Jun 03
Velcro crab (Camposcia retusa)
Upside down crab (showing its small undecorated pincers) righting itself. Changi, Dec 17

Velcro crabs on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores


Sembawang, Oct 20
Photo shared by Vincent Choo on facebook.


Pulau Ubin, Dec 17
Photo shared by Abel Yeo on facebook.

Beting Bronok, Jun 18

Photo shared by Loh Kok Sheng on facebook.


Tuas, Oct 12
Photo shared by Loh Kok Sheng on flickr.

East Coast Park, Apr 17
Photo shared by Loh Kok Sheng on facebook.


Sentosa, Apr 13
Photo shared by Marcus Ng on flickr.

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


Little Sisters Island, Jul 17
Photo shared by Jianlin Liu on facebook.

Sisters Island, Dec 10
Photo shared by Loh Kok Sheng on his blog.

Sisters Island, Jan 11
Photo shared by Loh Kok Sheng on his blog.


St. John's Island, Jul 10
Photo shared by Toh Chay Hoon on her blog.

St. John's Island, Sep 07
Photo shared by Loh Kok Sheng on his blog.

St. John's Island, Sep 07
Photo shared by Marcus Ng on flickr.


Pulau Tekukor, May 10
Photo shared by James Koh on flickr.

Pulau Hantu, Apr 12
Photo shared by Marcus Ng on flickr.

Terumbu Raya, Jul 14
Photo shared by Heng Pei Yan on flickr.

Filmed at Sisters Island, Dec 10

decorator crab (HD) from SgBeachBum on Vimeo.


Links References
  • Ng, Peter K. L. and Daniele Guinot and Peter J. F. Davie, 2008. Systema Brachyurorum: Part 1. An annotated checklist of extant Brachyuran crabs of the world. The Raffles Bulletin of Zoology. Supplement No. 17, 31 Jan 2008. 286 pp.
  • 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.
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