Crab
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Revert to revision 226049284 dated 2008-07-16 16:31:27 by Zaqarbal using [[:en:Wikipedia:Tools/Navigation_popups|popups]]
{{otheruses}}
{{Taxobox
| name = Crabs
| image = Blue crab on market in Piraeus - Callinectes sapidus Rathbun 20020819-317.jpg
| image_width = 250px
| image_caption = ''[[Blue crab|Callinectes sapidus]]''
| regnum = [[Animalia]]
| phylum = [[Arthropod]]a
| subphylum = [[Crustacean|Crustacea]]
| classis = [[Malacostraca]]
| ordo = [[Decapoda]]
| subordo = [[Pleocyemata]]
| infraordo = '''Brachyura'''
| infraordo_authority = [[Carolus Linnaeus|Linnaeus]], 1758
| subdivision_ranks = Superfamilies
| subdivision =
* '''Section [[Podotremata]]'''
**[[Cyclodorippoidea]]
**[[Homolodromidae|Homolodromioidea]]
**[[Dromioidea]]
**[[Homoloidea]]
**[[Raninoidea]]
* '''Section [[Eubrachyura]]'''
**'''Subsection [[Heterotremata]]'''
***[[Dorippoidea]]
***[[Calappoidea]]
***[[Leucosioidea]]
***[[Majoidea]]
***[[Hymenosomatidae|Hymenosomatoidea]]
***[[Parthenopoidea]]
***[[Retroplumidae|Retroplumoidea]]
***[[Cancroidea]]
***[[Portunoidea]]
***[[Bythograeidae|Bythograeoidea]]
***[[Xanthoidea]]
***[[Belliidae|Bellioidea]]
***[[Potamoidea]]
***[[Pseudothelphusidae|Pseudothelphusoidea]]
***[[Gecarcinucoidea]]
***[[Cryptochiridae|Cryptochiroidea]]
**'''Subsection [[Thoracotremata]]'''
***[[Pinnotheridae|Pinnotheroidea]]
***[[Ocypodoidea]]
***[[Grapsoidea]]
}}
'''Crabs''' are [[Decapoda|decapod]] [[crustacean]]s of the infraorder '''Brachyura''', which typically have a very short projecting "tail" ([[Greek language|Greek]]: ''brachy'' = short, ''ura'' = tail), or where the reduced abdomen is entirely hidden under the thorax. They are generally covered with a thick [[exoskeleton]], and are armed with a single pair of [[claw|chelae]] (claws). 6793 species are known.<ref>Walters, Martin & Johnson, Jinny. ''The World of Animals''. [[Bath, Somerset]]: [[Parragon]], [[2007]].</ref> Crabs are found in all of the world's oceans. Additionally, there are also many [[fresh water|freshwater]] and [[Land crab|terrestrial crabs]], particularly in tropical regions. Crabs vary in size from the [[pea crab]], only a few [[millimetre]]s wide, to the [[Japanese spider crab]], with a leg span of up to 4 [[metre|m]].<ref>{{cite web |url=http://oceanlink.island.net/records.html |title=Biggest, Smallest, Fastest, Deepest: Marine Animal Records |publisher=OceanLink |accessmonthday=September 22 |accessyear=2006}}</ref>
==Diet==
Crabs are decapods - 10 legged omnivores, but the front pair of legs are specialised with enlarged claws, so they are commonly described as 8 legged. Some feed primarily on algae, others taking any type of food, including mollusks, worms, other crustaceans, fungi, bacteria and detritus, depending on their availability and the crab species. For many crabs, a mixed diet of plant and animal matter results in the fastest growth and greatest fitness.
==Crab fishery==
{{Main|Crab fisheries}}
[[Image:Sorting Crabs Ffionphort.jpg|350px|thumb|left|[[Edible crab]]s being sorted by fishermen at [[Fionnphort]], [[Scotland]]]]
Crabs make up 20% of all marine [[crustacean]]s caught and farmed worldwide, with over 1½ million [[tonne]]s being consumed annually. Of that total, one species accounts for one fifth: ''[[Portunus trituberculatus]]''. Other important [[taxon|taxa]] include ''[[Portunus pelagicus]]'', several species in the genus ''[[Chionoecetes]]'', the [[blue crab]] (''Callinectes sapidus''), ''[[Charybdis (genus)|Charybdis spp.]]'', ''[[Edible crab|Cancer pagurus]]'', the [[Dungeness crab]] (''Cancer magister)'' and ''[[Scylla serrata]]'', each of which provides more than 20,000 tonnes annually <ref>{{cite web |url=http://www.fao.org/figis/servlet/TabLandArea?tb_ds=Capture&tb_mode=TABLE&tb_act=SELECT&tb_grp=COUNTRY |title=Global Capture Production 1950-2004 |publisher=[[Food and Agriculture Organization|FAO]] |accessmonthday=August 26 |accessyear=2006}}</ref>.
<br clear="left">
==Evolution and classification==
[[Image:Dungeness crab face closeup.jpg|thumb|left|The face of a [[dungeness crab]]. The two [[eye]]s sit on eyestalks, with two [[antennule]]s on either side of the [[rostrum (anatomy)|rostrum]] (center, above the mouth).]]
The infraorder Brachyura contains about 93 [[family (biology)|families]]<ref>[http://rmbr.nus.edu.sg/rbz/biblio/s17/s17rbz.pdf Systema Brachyurorum: Part 1. An Annotated checklist of extant Brachyuran crabs of the world] ''Raffles Bulletin of Zoology'', 2008, 286pp.</ref>, as many as the remainder of the [[Decapoda]].<ref name="Martin & Davis">{{cite book |url=http://www.nhm.org/research/publications/CrustaceaClassification.pdf |title=An Updated Classification of the Recent Crustacea |author=Martin, J. W. & G. E. Davis |year=2001 |pages=132 pp. |publisher=Natural History Museum of Los Angeles County |format=[[Portable Document Format|PDF]]}}</ref> The evolution of crabs is characterised by an increasing robustness of the body, and a reduction in the abdomen. Although other groups have also undergone similar processes of [[carcinisation]], it is most advanced in crabs. The [[telson]] is no longer functional in crabs, and the [[uropod]]s are absent, having probably evolved into small devices for holding the reduced abdomen tight against the sternum.<ref>{{cite journal | quotes=no |author=Guinot, D & J.–M. Bouchard |year=1998 |title=Evolution of the abdominal holding systems of brachyuran crabs (Crustacea, Decapoda, Brachyura) |journal=[[Zoosystema]] |volume=20 |issue=4 |pages=613–694 |url=http://www.mnhn.fr/publication/zoosyst/z98n4a4.html |format=[[Portable Document Format|PDF]]}}</ref>
In most decapodists, the [[gonopore]]s (sexual openings) are found on the legs. However, since crabs use the first two pairs of [[pleopod]]s (abdominal appendages) for [[sperm transfer]], this arrangement has changed. As the male abdomen evolved into a narrower shape, the gonopores have moved towards the midline, away from the legs, and onto the [[Sternum (arthropod)|sternum]].<ref>{{cite journal | quotes=no |author=De Saint Laurent, M. |year=1980 |title=Sur la classification et la phylogénie des Crustacés Décapodes Brachyoures. II. Heterotremata et Thoracotremata Guinto, 1977 |journal=[[C. R. Acad. Sc. Paris]] |volume=t. 290 |pages=1317–1320}}</ref> A similar change occurred, independently, with the female gonopores. The movement of the female gonopore to the sternum defines the [[clade]] [[Eubrachyura]], and the later change in the position of the male gonopore defines the [[Thoracotremata]]. It is still a subject of debate whether those crabs where the female, but not male, gonopores are situated on the sternum form a [[Monophyly|monophyletic group]].<ref name="Martin & Davis"/>
The earliest unambiguous crab [[fossil]]s date from the [[Jurassic]], although the [[Carboniferous]] ''[[Imocaris]]'', known only from its [[carapace]] is thought to be a primitive crab.<ref>{{cite journal | quotes=no |author=[[Frederick Schram|Schram, F. R.]] & R. Mapes |year=1984 |title=''Imocaris tuberculata'', n. gen., n. sp. (Crustacea: Decapoda) fro the upper Mississippian Imo Formation, Arkansas |journal=[[Transactions of the San Diego Society of Natural History]] |volume=20 |issue=11 |pages=165–168}}</ref> The [[Adaptive radiation|radiation]] of crabs in the [[Cretaceous]] and afterwards may be linked either to the break-up of [[Gondwana]] or to the concurrent radiation of [[Osteichthyes|bony fish]], the main [[predator]]s of crabs.<ref>{{cite journal | quotes=no |author=Wägele, J. W. |year=1989 |title=On the influence of fishes on the evolution of benthic crustaceans |journal=J. zool. Syst. Evolut.-forsch. |volume=27 |pages=297–309}}</ref>
About 850 species<ref>{{cite journal | quotes=no |author=Sternberg, R. von & N. Cumberlidge |year=2001 |title=On the heterotreme-thoracotreme distinction in the Eubrachyura De Saint Laurent, 1980 (Decapoda: Brachyura) |journal=[[Crustaceana]] |volume=74 |pages=321–338 |doi=10.1163/156854001300104417}}</ref> of crab are freshwater or (semi-)terrestrial species; they are found throughout the world's [[tropic]]al and [[Subtropics|semi-tropical]] regions. They were previously thought to be a closely related group, but are now believed to represent at least two distinct [[Lineage (evolution)|lineages]], one in the [[Old World]] and one in the [[New World]].<ref>{{cite journal | quotes=no |author=Sternberg, R. von, N. Cumberlidge & G. Rodriguez |year=1999 |title=On the marine sister groups of the freshwater crabs (Crustacea: Decapoda: Brachyura) |journal=[[J. Zool. Syst. Evol. Research]] |volume=37 |pages=19–38 |doi=10.1046/j.1439-0469.1999.95092.x}}</ref>
==Cultural influences of the crab==
[[Image:Vasija mochica crustáceo (M. América Inv.1409) 01.jpg|thumb|120px|right|Moche vessel representing a crab.]]
The [[Moche]] people of ancient [[Peru]] worshipped nature, especially the sea.<ref> Benson, Elizabeth, The Mochica: A Culture of Peru. New York, NY: Praeger Press. 1972</ref> They placed emphasis on animals and often depicted crabs in their art.<ref>Berrin, Katherine & Larco Museum. ''The Spirit of Ancient Peru:Treasures from the [[Larco_Museum|Museo Arqueológico Rafael Larco Herrera]].'' New York: [[Thames and Hudson]], 1997.</ref>
==Gallery==
<gallery>
Image:Corystes cassivelaunus.jpg|[[Masked crab]], ''Corystes cassivelaunus''
Image:Liocarcinus vernalis.jpg|''[[Liocarcinus vernalis]]''
Image:Atelecyclus rotundatus.jpg|[[Circular crab]], ''Atelecyclus rotundatus''
Image:Gecarcinus ruricola.jpg|The terrestrial [[halloween crab]], ''Geocarcinus ruricola''
Image:Stenorhynchus seticornis 2.jpg|[[Arrow crab]] ''Stenorhynchus seticornis''
Image:Grapsus grapsus.JPG|"[[Sally Light Foot]]", ''[[Grapsus grapsus]]''
Image:Thia scutellata.jpg|[[Thumbnail crab]], ''Thia scutellata''
Image:Spider crabs at the Kaiyukan Aquarium in Osaka close.jpg|[[Japanese spider crab]], ''Macrocheira kaempferi''
Image:Ocypode quadrata (2).jpg|[[Ghost crab]], ''Ocypode quadrata''
Image:Fiddler crab.jpg|[[Fiddler crab]], ''Uca pugnax''
Image:Lyreidus tridentatus.jpg|''Lyreidus tridentatus'', a [[Raninidae|raninid]]
Image:Hepatus epheliticus.jpg|''Hepatus epheliticus'', a calico crab
Image:Crab larva.jpg|Crab larva ([[megalopa]])
</gallery>
==References==<!-- Zootaxa 1558: 39 -->
{{reflist|2}}
== See also ==
{{col-begin}}
{{col-4}}
* [[Arrow crab]]
* [[Blue Crab]]
* [[Calappa (crab)|Calappa crab]]
* [[Chinese mitten crab]]
* [[Crab-eating Macaque]]
* [[Crab-eating Raccoon]]
* [[Dungeness crab]]
{{col-4}}
* [[Emerald Crab]]
* [[Florida stone crab]]
* [[Giant crab]]
* [[Hippoidea]]
* [[Horsehair crab]]
* [[Jonah crab]]
* [[Lady crab]]
{{col-4}}
* [[Land crab]]
* [[Mangrove crab]]
* [[Mud crab]]
* [[Paralithodes camtschaticus]]
* [[Red crab]]
* [[Sand bubbler crab]]
* [[Seaweed decorator crab]]
{{col-4}}
* [[Soft-shell crab]]
* [[Soldier crab]]
* [[Spider crab]]
* [[Stilt crab]]
* [[Strawberry crab]]
* [[Tasmanian giant crab]]
* [[Velvet crab]]
{{col-end}}
==External links==
{{commonscat-inline|Brachyura}}
{{Wikispecies-inline|Brachyura}}
{{fisheries and fishing}}
[[Category:Crabs| ]]
[[Category:Edible crustaceans]]
[[Category:Commercial crustaceans]]
[[ang:Crabba (dēor)]]
[[zh-min-nan:Hē]]
[[ca:Cranc]]
[[cs:Krabi]]
[[da:Krabbe]]
[[de:Krabben]]
[[et:Krabilised]]
[[es:Brachyura]]
[[eo:Krabo]]
[[fr:Brachyura]]
[[gd:Partan]]
[[ko:게]]
[[hr:Rakovi]]
[[id:Kepiting]]
[[it:Brachyura]]
[[ht:Krab]]
[[la:Cancer]]
[[lt:Krabas]]
[[mg:Foza]]
[[ms:Ketam]]
[[nah:Tecuicihtli]]
[[nl:Krabben]]
[[ja:カニ]]
[[no:Krabber]]
[[pl:Kraby]]
[[pt:Caranguejo]]
[[ro:Crab]]
[[ru:Крабы]]
[[fi:Taskuravut]]
[[sv:Krabbor]]
[[tl:Alimango]]
[[ta:நண்டு]]
[[th:ปู]]
[[vi:Cận bộ Cua]]
[[tr:Yengeç]]
[[uk:Краби]]
[[vls:Krabbe]]
[[zh:螃蟹]]