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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans
Spider crabs
Superfamily Majoidea
updated Dec 12

if you learn only 3 things about them ...
They are often very well camouflaged. Look out for unusual movement.
Some are tiny and look like bits of dirt.
They have pointed heads and long skinny legs.

Where seen? Spider crabs are encountered on all our shores. But they're hard to spot. In addition to being slow-moving and well camouflaged, many are also small.

Features: Body width 0.5-3cm. These crabs are well disguised. They have long, skinny legs that give them their common name. Some have legs and bodies that resemble roots or other bits of debris so they blend perfectly with their surroundings. Body usually triangular, tapering to a point at the head with the small eyes on the sides of the tip. The body is often covered with spines, knobs and hooked hairs. Some decorate themselves with living seaweeds, sponge, other animals or bits of coral and rubbish.They are also slow-moving, so it's hard to penetrate their disguise.

Special Spider: Our tiny spider crabs are cousins of the biggest crab in the world! The Japanese spider crab (Macrocheira kaempferi), with a leg span of 4m, belongs to the same family.

Human uses:
Unfortunately, the Velcro crab (Camposcia retusa) is among those sold in the live aquarium trade. Some large spider crabs in temperate seas are important commercially as seafood. They are harvested by the ton. These include the Canadian snow crab (Chionoecetes opilio) which can have a body width of about 16cm, leg span of 90cm, and weigh more than 1kg; and the European spiny spider crab (Maja squinado) which can have a body width of 8.5-20cm and pincers up to 1m long!

Status and threats:
One of our spider crabs are listed among the threatened animals in Singapore.
However, like other creatures of the intertidal zone, they are affected by human activities such as reclamation and pollution. Trampling by careless visitors and over-collection can also have an impact on local populations.


Decorated upperside

Underside, only the pincers are 'undecorated'.
Chek Jawa, Aug 05


Almost impossible to spot until it moves.
Cyrene Reef, Jul 10

Spider crabs on Singapore shores


Superfamily Majoidea recorded for Singapore
from Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore
*from Tan, Leo W. H. & Ng, Peter K. L., 1988. A Guide to Seashore Life.
**from Lim, S., P. Ng, L. Tan, & W. Y. Chin, 1994. Rhythm of the Sea: The Life and Times of Labrador Beach.
***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.
in red are those listed among the threatened animals of Singapore from 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.


  Spider crabs seen awaiting identification
Species are difficult to positively identify without close examination.
On this website, they are grouped by external features for convenience of display.
  Tiny spider crabs

  Family Majidae
  Micippa excavata
**Micippa philyra

*Planotergum mirabile
(EN: Endangered)

Schizophrys sp. (Sea toad spider crab)
Schizophrys aspera
Schizophrys dama

  ***Family Epialtidae (previously Majidae)
  Chlorinoides gemaini

*Doclea canaliformis
(EN: Endangered)

Hyastenus aries
Hyastenus diacanthus
Hyastenus elatus (EN: Endangered)
Hyastenus sebae

Hyastenus subinermis (EN: Endangered)

Menatheius sp. (Arrow-head spider crab)
**
Menaethius monoceros (One-horned spider crab) (VU: Vulnerable)

Phalangipus arachnoides

Tylocarcinus styx

Xenocarcinus tuberculatus

  ***Family Inachidae (previously Majidae)
  Camposcia retusa (Velcro crab) (VU: Vulnerable)

Paratymolus cygnus
(CR: Critically endangered)
Paratymolus pubescens

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. (Online PDF on the Raffles Bulletin of Zoology website)
  • 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.
  • Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore. National Council on the Environment. 163pp.
  • 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.
  • Debelius, Helmut, 2001. Crustacea Guide of the World: Atlantic Ocean, Indian Ocean, Pacific Ocean IKAN-Unterwasserachiv, Frankfurt. 321 pp.
  • Gosliner, Terrence M., David W. Behrens and Gary C. Williams. 1996. Coral Reef Animals of the Indo-Pacific: Animal life from Africa to Hawai’I exclusive of the vertebrates Sea Challengers. 314pp.
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