Halloween crab

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Halloween crab

Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Order:	Decapoda
Infraorder:	Brachyura
Family:	Gecarcinidae
Genus:	Gecarcinus
Species:	G. quadratus

Binomial name

Gecarcinus quadratus
de Saussure, 1853

The Halloween crab (Gecarcinus quadratus), also known as the Moon crab, Mouthless crab or Harlequin land crab, is a colourful land crab from the family Gecarcinidae. It is found in mangrove, sand dunes and rainforest along the Pacific coast from Mexico south to Peru. The taxonomy in relations to the Atlantic Gecarcinus lateralis is disputed, with many considering it and G. quadratus to be conspecific.

In the pet-trade it is sometimes confused with the African Cardisoma armatum (sometimes also referred to as the Moon crab) or the primarily Caribbean Gecarcinus ruricola. Unlike these, G. quadratus combines a pair of largely purple claws, reddish-orange legs, and an almost entirely blackish (actually dark brownish if seen well) carapace with a pair of yellow, orange or maroon spots behind the eyes, and an additional pair of whitish spots on the central-lower carapace. Additionally, the name Halloween crab sometimes leads to confusion with the entirely different halloween hermit crab. The carapace of G. quadratus may reach a length of 5 cm (2 in).

This nocturnal crab digs burrows - sometimes as long as 1,5 m (5 ft) - in the coastal rainforests of Central America, and is common in parts of Costa Rica. There it lives in the forest at least some of its adult life, but needs to return to the ocean to breed. They have gills that need to be moist all the time. If not, they die. The halloween crab is very territorial and will defend itself if threatened. It is largely herbivorous, and consumes leaf litter and seedlings. They will, however, also take animal matter if available.

A dead specimen of G. quadratus on the Pacific coast of Costa Rica.

[edit] References

Bright, D., & C. Hogue. 1972. A synopsis of burrowing land crabs of the World and list of their arthropod symbionts and burrow associates. Contributions in Science. No. 220. Available online (PDF)
Sällström, S., K. Nygren, & I. Lindquist. 2002. Selective food choice and distribution of Mouthless crabs (Gecarcinus quadratus), in Corcovado National Park, Costa Rica. Ecological methods. SLU, Uppsala 2002.
Sherman, P. 2006. Influence of land crabs Gecarcinus quadratus (Gecarcinidae) on distributions of organic carbon and roots in a Costa Rican rain forest. Rev. Biol. Trop. Vol. 54(1): 149-161.
Halloween Crab. The Firefly Forest. Accessed March 9, 2008