Plunger Stephan
Montag, 28. Februar 2011
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They are characterized by breathing air, laying shelled eggs, and having skin covered in scales and/or scutes. Reptiles are classically viewed as having a "cold-blooded" metabolism. They are have four limbs or descend from four-limbed ancestors. Modern reptiles inhabit every continent with the exception of Antarctica, and four living orders are currently recognized:
•Crocodilia (crocodiles, gavials, caimans, and alligators): 23 species
•Sphenodontia (tuataras from New Zealand): 2 species
•Squamata (lizards (Echsen), snakes, and worm lizards): approximately 7,900 species
•Testudines (turtles and tortoises): approximately 300 species
Contrary to amphibians, reptiles do not have an aquatic larval stage. As a rule, reptiles are egg-laying, although certain species of squamates are capable of giving live birth. Many of the live-birthing species feed their fetuses through various forms of placenta like mammals, with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, that grows to only 1.6 cm (0.6 in) to the saltwate crocodile that may reach 6 m in length and weigh over 1,000 kg. The science dealing with reptiles is called herpetology.
>There are more than 8,000 species of reptiles on the planet, and the live on every continent except Antarctica (where it is too cold).
>"Cold-blooded" is not the best way to describe reptiles. Their blood is not necessarily cold by itself. But they are ectothermic, which means they get their body heat from external sources. Reptiles cannot regulate their body temperature internally as humans do
>Most of the world's snakes (nearly two-thirds) are non-venomous. Only about 500 snake species are venomous, and of those only 30 - 40 are considered harmful to humans. In other words, less than 2 percent of all snakes are considered harmful to humans.
>Most kinds of reptiles do not tolerate the cold very well. But the Blanding's turtle is sometimes found swimming under the ice in the Great Lakes region of the United States.
>Many people think that reptiles are slimy. But the fact is that reptiles do not have sweat glands like you and I have, so their skin is usually cool and dry. People who touch reptiles for the first time always say the same thing: "Oh wow, they're not slimy at all."
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Kategorie:
vertebrates