Crab

*Dromiacea *Raninoida *Heterotremata *Thoracotremata The term crab is often applied to several different groups of short (nose to tail) Decapodas 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 Anomala and can be distinguished from true crabs by counting the legs - in Anomala, 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. ==True crabs== True crabs are crustaceans in the suborder Brachyura, in the Order (biology) Decapoda. They have five pairs of walking legs (the first of which is modified into a pair of claws or ''chelae'') and typically a flattened shell. In all but a few crabs (for example, Raninoida), the abdomen is folded under the cephalothorax. The form of the abdomen usually reveals the sex of the crab - males have a narrow abdomen, while females have a much wider abdomen, under which they carry their egg (biology). Crabs are a very diverse group, mostly found in salt water, but with some groups living in freshwater or on land. Although famed for their tendency to walk sideways, crabs are in fact able to walk in any direction. Classification within the crabs is traditionally based on the position of the gonopores: whether they are found on the legs or on the thorax. In the two "primitive" sections (sometimes called collectively the "Podotremata"), the gonopores are found on the legs (as in all other decapods); in the Heterotremata, the male gonopores are on the legs, and the female gonopores are on the sternum; in the Thoracotremata, the gonopores are on the sternum in both males and females. ==Other animals== A number of animals with a similar shape are commonly called crabs, including the crab louse (an insect) and the horseshoe crab (in the class Merostomata). The crab louse is the origin of the slang term "crabs" for an infestation of pubic lice. ==Superfamily== * Bellioidea * Bythograeoidea * Calappoidea * Cancroidea * Cryptochiroidea * Cyclodorippoidea * Dorippoidea * Dromioidea * Gecarcinucoidea * Grapsoidea * Homolodromioidea * Homoloidea * Hymenosomatoidea * Leucosioidea * Majoidea * Ocypodoidea * Parthenopoidea * Pinnotheroidea * Portunoidea * Potamoidea * Pseudothelphuspoidea * Raninoidea * Retroplumoidea * Xanthoidea ==External links== * ''Brachyura'' entry at [http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=98276 ITIS Report] * ''Brachyura'' entry at [http://animaldiversity.ummz.umich.edu/site/accounts/classification/Brachyura.html#Brachyura Animal diversity web] *[http://ww2.lafayette.edu/~hollidac/research.html Prof. Chuck Holliday's Research Page], Prof. Chuck Holliday, Dept. of Biology, Lafayette College. Contains links to articles on osmoregulation in crabs and other crustaceans. Crabs Seafood

Crab

do crabs claws go back

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C

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Words begining with Crab:

Crab
Crab
Crab-apple
Crab-Eating_Fox
Crab-eating_fox
Crab-eating_fox
Crab-Eating_Macaque
Crab-Eating_Macaque
Crab-eating_Macaque
Crab-eating_Macaque
Crab-eating_macaque
Crab-plover
Crabapple
Crabbe
Crabben
Crabby_Cabbie
Crabeater
Crabeater_Seal
Crabeater_Seal
Crabeater_seal
Crabeater_seal
Crabgrass
Crabier
Crablogger
Crablogger
Crabmeat
Crabmon
Crabmon_X
Crabronidae
Crabs
Crabs
Crabstreetjournal
Crabtree,_PA
Crabtree,_Pennsylvania
Crabtree_Valley_Mall
Crabwalk
Crab_(disambiguation)
Crab_Apple
Crab_apple
Crab_Cactus
Crab_canon
Crab_canon
Crab_Cavity
Crab_grass
Crab_Lake,_Minnesota
Crab_Lake,_MN
Crab_Landing
Crab_landing
Crab_landing
Crab_louse
Crab_mentality
Crab_Nebula
Crab_nebula
Crab_Orchard
Crab_Orchard,_Kentucky
Crab_Orchard,_KY
Crab_Orchard,_NE
Crab_Orchard,_Nebraska
Crab_Orchard,_Tennessee
Crab_Orchard,_TN
Crab_Orchard,_West_Virginia
Crab_Orchard,_WV
Crab_Orchard_Mountains
Crab_Plover
Crab_plover
Crab_Pulsar
Crab_rangoon
Crab_soccer
Crab_Spider
Crab_spider
Crab_spider
Crab_stick