Corystes cassivelaunus, the masked crab, helmet crab or sand crab,[1] is a burrowing crab of the North Atlantic and North Sea from Portugal to Norway, which also occurs in the Mediterranean Sea.[2] It may grow up to 4 centimetres or 1.6 inches long (carapace length).[1] The name "masked crab" derives from the patterns on the carapace which resemble a human face (a case of pareidolia), in a similar manner to heikegani.[3] It is the only species in the genus Corystes.[4]

Corystes cassivelaunus
Corystes cassivelaunus 1.jpg
A male C. cassivelaunus
Scientific classification edit
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Family: Corystidae
Genus: Corystes
Bosc, 1802
C. cassivelaunus
Binomial name
Corystes cassivelaunus
(Pennant, 1777)
  • Cancer cassivelaunus Pennant, 1777
  • Hippa dentata Fabricius, 1793
  • Cancer personatus Herbst, 1785
  • Albunea dentata Fabricius, 1798
  • Corystes dentatus Latreille, 1801

C. cassivelaunus lives buried in sandy substrates, where it feeds on the infaunal invertebrates such as polychaete worms and bivalve molluscs.[1] It uses its two antennae to form a breathing tube that allows oxygenated water down into the substrate.[5][6] The chelipeds of males are much longer than the body, while those of females are only about as long as the carapace.[7]


  1. ^ a b c "Masked crab (Corystes cassivelaunus)". Archived from the original on 2004-12-26. Retrieved November 14, 2006.
  2. ^ "Crabs of the Southern North Sea". Department Zeevisserij (Sea Fisheries Department). October 8, 2001. Archived from the original on December 18, 2007.
  3. ^ Webster's Revised Unabridged Dictionary (1913). masked crab. Archived from the original on 2011-07-14. Retrieved 2006-11-14.
  4. ^ Peter Davie & Michael Türkay (2011). "Corystes Bosc, 1802". WoRMS. World Register of Marine Species. Retrieved June 7, 2012.
  5. ^ "Helmkrab" (in Dutch). Retrieved January 9, 2010.
  6. ^ "Masked crab, Corystes cassivelaunus". Sefton Coast.
  7. ^ M. J. De Kluijver. & S. S. Ingalsuo. "Corystes cassivelaunus". Macrobenthos of the North Sea: Crustacea. Universiteit van Amsterdam. Archived from the original on 2011-07-17. Retrieved January 9, 2010.