Animal

characteristics of reptiole:

dry scales on skin

4limbs with digits

terrestrial (eg. snake,turtle,crocodile and lizard)

cold blooded

firstly, we know that tortoises are cold blooded, as it moves slowly during night time,also they will 冬眠during the winter

secondly, it has dry scales on its skin (in order to keep enough water for itself)

i think that u are asking why turtle is not amphibian but reptile

actually

amphibian is naked,(i mean they dont have dry scales on their skin)

they need to live near the river in order to keep their body wet (eg.frog)

also, their body produce mucus to keep themselves wet

moreover, amphibian use its lungs to proceed respiration

while turtles do not sry turtle uses its lungs to take breathing and out

2009-04-27 22:44:10 補充：
鱉，即俗稱水魚，是兩棲類(amphibian)。根據生物的分類定律，兩棲類的特徵是有濕滑和帶粘液的皮膚，且呼吸可以在皮膚上進行。牠和青蛙是同類的。

2009-04-27 22:44:37 補充：
amphibian:綠色的龜，即殼屬硬的那類，是爬行類(retile)。因為牠有堅硬和乾燥的鱗狀表皮，且有肺呼吸。與蛇、蜥蝪是同一類。

Amphibians :
Amphibians (class - Amphibia) are cold-blooded animals that metamorphose from a juvenile, water-breathing form to an adult, air-breathing form. Typically, amphibians have four limbs. Unlike other land animals (amniotes), amphibians lay eggs in water, as their fish ancestors did. Amphibians are superficially similar to reptiles.
Frogs, toads, salamanders, newts and caecilians.
Reptiles :
Reptiles (class - Reptilia) are air-breathing, cold-blooded amniotes that have skin covered in scales or scutes as opposed to hair or feathers. They are tetrapods (having or having descended from vertebrates with four limbs) and lay amniote eggs, whose embryos are surrounded by the amnion membrane. Modern reptiles inhabit every continent with the exception of Antarctica.
Crocodiles, gavials, caimans, alligators, turtles, tortoises, terrapins, tuatara, lizards, iguanas, komodo dragons, chameleons, xantusiids (night lizards), typhlopids (blind snakes), geckos, snakes, amphisbaenids (worm-lizards or the slow worm) and the extinct relatives - dinosaurs ( terrible lizards ).