Saturday, April 25, 2009

Crab




Callinectes sapidus








Scientific classification

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata

Sections
  • Dromiacea
  • Raninoida
  • Heterotremata
  • Thoracotremata
The term crab is often applied to several different groups of short (nose to tail) decapod crustaceans with thick exoskeletons, but only members of the Brachyura are true crabs; other taxa, such as hermit crabs, porcelain crabs, king crabs, and horseshoe crabs are, despite superficial similarities, not crabs at all. Hermit crabs, king crabs and porcelain crabs belong to the Anomura and can be distinguished from true crabs by counting the legs - in Anomura, the last pair of pereiopods (walking legs) is hidden inside the carapace and so only four pairs are visible (counting the claws), whereas uninjured true crabs always have five visible pairs.

The term crab is often applied to several different groups of short (nose to tail) decapod crustaceans with thick exoskeletons, but only members of the Brachyura are true crabs; other taxa, such as hermit crabs, porcelain crabs, king crabs, and horseshoe crabs are, despite superficial similarities, not crabs at all. Hermit crabs, king crabs and porcelain crabs belong to the Anomura and can be distinguished from true crabs by counting the legs - in Anomura, the last pair of pereiopods (walking legs) is hidden inside the carapace and so only four pairs are visible (counting the claws), whereas uninjured true crabs always have five visible pairs.

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