Reptiles are tetrapods and amniotes, animals whose embryos are surrounded by an amniotic membrane. Today they are represented by four surviving orders:

• Crocodilia (crocodiles, caimans and alligators): 23 species
• Rhynchocephalia (tuataras from New Zealand): 2 species
• Squamata (lizards, snakes and amphisbaenids ("worm-lizards")): approximately 7,600 species
• Testudines (turtles): approximately 300 species

Reptiles are found on every continent except for Antarctica, although their main distribution comprises the tropics and subtropics. Though all cellular metabolism produces some heat, modern species of reptiles do not generate enough to maintain a constant body temperature and are thus referred to as "cold-blooded" (ectothermic). (See the Leatherback Sea Turtle for an exception: a reptile that elevates its body temperature well above that of its surroundings.) Instead they rely on gathering and losing heat from the environment to regulate their internal temperature, e.g, by moving between sun and shade, or by preferential circulation — moving warmed blood into the body core, while pushing cool blood to the periphery. In their natural habitats, most species are adept at this, and can maintain core body temperatures within a fairly narrow range, comparable to that of mammals and birds, the two surviving groups of "warm-blooded" animals. While this lack of adequate internal heating imposes costs relative to temperature regulation through behavior, it also provides a large benefit by allowing reptiles to survive on much less food than comparably-sized mammals and birds, who burn much of their food for warmth. While warm-blooded animals move faster in general, an attacking lizard, snake or crocodile moves very quickly. A herpetologist is a zoologist who studies reptiles and amphibians.

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Caribbean Amphibians and Reptiles http://bit.ly/16mTD9
UnderwaterGal (Di Wilson) Sat, 07 Nov 2009 00:29:37 -0000
Caribbean Amphibians and Reptiles http://bit.ly/16mTD9
Mutated reptiles and amphibians offer new and previously unimagined taste sensations.
franzferdinand2 (franzferdinand2) Fri, 06 Nov 2009 17:45:08 -0000
Mutated reptiles and amphibians offer new and previously unimagined taste sensations.
Knows the difference between reptiles and amphibians.
chuckfive (charlie gschwend) Fri, 06 Nov 2009 17:43:01 -0000
Knows the difference between reptiles and amphibians.
Scientists propose a 'genome zoo' of every genus of birds, mammals, reptiles, amphibians, and fishes -- any animal with a spine!
familybuilder (Familybuilder) Thu, 05 Nov 2009 15:34:53 -0000
Scientists propose a 'genome zoo' of every genus of birds, mammals, reptiles, amphibians, and fishes -- any animal with a spine!
What does a herpetologist study? "Reptiles and amphibians"
SlyBilly (BillyD) Thu, 05 Nov 2009 14:07:20 -0000
What does a herpetologist study? "Reptiles and amphibians"
What does a herpetologist study? "Reptiles and amphibians"
SlyBilly (BillyD) Thu, 05 Nov 2009 00:07:21 -0000
What does a herpetologist study? "Reptiles and amphibians"

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