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Created page with 'File:lighterstill.jpgRight|frame '''Reptiles''' are animals in the ([http://en.wikipedia.org/wiki/Linnaean_taxonomy Linnaean]) class Reptilia char...'
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'''Reptiles''' are [[animals]] in the ([http://en.wikipedia.org/wiki/Linnaean_taxonomy Linnaean]) class Reptilia characterized by [[breathing]] [[air]], a "cold-blooded" (poikilothermic) [[metabolism]], laying tough-shelled [http://en.wikipedia.org/wiki/Amniote amniotic eggs] (or retaining the same membrane system in [[species]] with live [[birth]]), and skin with scales or scutes. They are [http://en.wikipedia.org/wiki/Tetrapod tetrapods] (either having four limbs or being descended from four-limbed [[ancestors]]) and lay [http://en.wikipedia.org/wiki/Amniote amniotic eggs], in which the embryo is surrounded by a membrane called the [http://en.wikipedia.org/wiki/Amnion amnion]. Modern reptiles inhabit every continent with the exception of Antarctica, and four living [[orders]] are currently [[recognized]]:
* ''[http://en.wikipedia.org/wiki/Crocodilia Crocodilia]'' (crocodiles, gavials, caimans, and alligators): 23 species
* ''[http://en.wikipedia.org/wiki/Sphenodontia Sphenodontia]'' (tuataras from New Zealand): 2 species
* ''[http://en.wikipedia.org/wiki/Squamata Squamata]'' (lizards, snakes, and worm lizards): approximately 7,900 species
* ''[http://en.wikipedia.org/wiki/Testudines Testudines]'' (turtles and tortoises): approximately 300 species
The [[majority]] of reptile species are ''oviparous'' (egg-laying), although certain [[species]] of squamates are capable of giving live birth. This is achieved by either ovoviviparity (egg retention) or viviparity ([[birth]] of offspring without the development of calcified eggs). Many of the viviparous species feed their fetuses through various forms of [http://en.wikipedia.org/wiki/Placenta placenta] [[analogous]] to those of [[mammals]], with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, [http://en.wikipedia.org/wiki/Jaragua_Sphaero Sphaerodactylus ariasae], that [[grows]] to only 1.6 cm (0.6 in) to the [http://en.wikipedia.org/wiki/Saltwater_Crocodile saltwater crocodile], Crocodylus porosus, that may reach 6 m in length and weigh over 1,000 kg. The [[science]] dealing with ''reptiles'' is called [http://en.wikipedia.org/wiki/Herpetology herpetology].[http://en.wikipedia.org/wiki/Reptiles]
[[Category: Biology]]
[[Category: Zoology]]
'''Reptiles''' are [[animals]] in the ([http://en.wikipedia.org/wiki/Linnaean_taxonomy Linnaean]) class Reptilia characterized by [[breathing]] [[air]], a "cold-blooded" (poikilothermic) [[metabolism]], laying tough-shelled [http://en.wikipedia.org/wiki/Amniote amniotic eggs] (or retaining the same membrane system in [[species]] with live [[birth]]), and skin with scales or scutes. They are [http://en.wikipedia.org/wiki/Tetrapod tetrapods] (either having four limbs or being descended from four-limbed [[ancestors]]) and lay [http://en.wikipedia.org/wiki/Amniote amniotic eggs], in which the embryo is surrounded by a membrane called the [http://en.wikipedia.org/wiki/Amnion amnion]. Modern reptiles inhabit every continent with the exception of Antarctica, and four living [[orders]] are currently [[recognized]]:
* ''[http://en.wikipedia.org/wiki/Crocodilia Crocodilia]'' (crocodiles, gavials, caimans, and alligators): 23 species
* ''[http://en.wikipedia.org/wiki/Sphenodontia Sphenodontia]'' (tuataras from New Zealand): 2 species
* ''[http://en.wikipedia.org/wiki/Squamata Squamata]'' (lizards, snakes, and worm lizards): approximately 7,900 species
* ''[http://en.wikipedia.org/wiki/Testudines Testudines]'' (turtles and tortoises): approximately 300 species
The [[majority]] of reptile species are ''oviparous'' (egg-laying), although certain [[species]] of squamates are capable of giving live birth. This is achieved by either ovoviviparity (egg retention) or viviparity ([[birth]] of offspring without the development of calcified eggs). Many of the viviparous species feed their fetuses through various forms of [http://en.wikipedia.org/wiki/Placenta placenta] [[analogous]] to those of [[mammals]], with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, [http://en.wikipedia.org/wiki/Jaragua_Sphaero Sphaerodactylus ariasae], that [[grows]] to only 1.6 cm (0.6 in) to the [http://en.wikipedia.org/wiki/Saltwater_Crocodile saltwater crocodile], Crocodylus porosus, that may reach 6 m in length and weigh over 1,000 kg. The [[science]] dealing with ''reptiles'' is called [http://en.wikipedia.org/wiki/Herpetology herpetology].[http://en.wikipedia.org/wiki/Reptiles]
[[Category: Biology]]
[[Category: Zoology]]