Reptiles are tetrapods and amniotes, animals whose embryos are surrounded by an amniotic membrane. These days they’re represented by 4 surviving orders:
Crocodilia (crocodiles, caimans and alligators): 23 species
Sphenodontia (tuataras from New Zealand): two species
Squamata (lizards, snakes and amphisbaenids (“worm-lizards”)): roughly 7,600 species
Testudines (turtles): roughly 300 species
Reptiles live on each continent except for Antarctica, even though their primary distribution comprises the tropics and subtropics. Although all cellular metabolism produces some heat, most contemporary species of reptiles don’t produce sufficient to preserve a continuous physique temperature and are therefore known as “cold-blooded” or ectothermic (the Leatherback Sea Turtle is definitely an exception). Rather, they depend on gathering and losing heat in the atmosphere to regulate their internal temperature, e.g, by moving in between sun and shade, or by preferential circulation – moving warmed blood in to the physique core, whilst pushing cool blood towards the periphery. In their all-natural habitats, most species are adept at this, and may usually preserve core physique temperatures inside a pretty narrow variety, comparable to that of mammals and birds, the two surviving groups of “warm-blooded” animals. Whilst this lack of sufficient internal heating imposes expenses relative to temperature regulation via behavior, additionally, it offers a sizable advantage by permitting reptiles to survive on a lot much less meals than comparably-sized mammals and birds, who burn a lot of their meals for warmth. Whilst warm-blooded animals move quicker generally, an attacking lizard, snake or crocodile moves extremely rapidly.
Except for a couple of members from the Testudines, all reptiles are covered by scales.
Most reptile species are oviparous (egg-laying). Numerous species of squamates, nevertheless, are capable of providing live birth. This really is accomplished, either via ovoviviparity (egg retention), or viviparity (babies born with out use of calcified eggs). Numerous from the viviparous species feed their fetuses via numerous types of placenta analogous to the mammals (Pianka & Vitt, 2003 pgs: 116-118). They often provide considerable initial care for their hatchlings.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia.
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