Man frogs are able to absorb water and oxygen directly through the skin, especially around the pelvic area. However, the permeability of a frog's skin can also result in water loss. Some tree frogs reduce water loss with a waterproof layer of skin. Others have adapted behaviours to conserve water, including engaging innocturnalactivity and resting in a water-conserving position. This position involves the frog lying with its toes and fingers tucked under its body and chin, respectively, with no gap between the body and substrate. Some frog species will also rest in large groups, touching the skin of the neighbouring frog. This reduces the amount of skin exposed to the air or a dry surface, and thus reduces water loss. These adaptations only reduce water loss enough for a predominantly arboreal existence, and are not suitable for arid conditions.
How do reptiles breath
Reptilian skin is covered in a hornyepidermis, making it watertight and enable reptiles to live on dry land, in contrast to the amphibians. Compared to mammals, reptilian skin is rather thin, and lack the thickdermallayer that producesleatherin mammals.[30]Exposed parts of reptiles are protected by hornyscalesorscutes, sometimes with a bony base, formingarmour. In turtles, the body is hidden inside a hard shell composed on fused scutes. In thelepidosaurianslike lizards and snakes, the whole skin is covered inepidermalscales (seeReptilescales). Such scales where once thought to be typical of the class Reptilia as a whole, but are really only found in the lepidosaurians. The scales found in turtles and crocodiles are ofdermalorigin rather than epidermal, and are properly termed scutes.
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发表于 2009-6-13 10:12:00
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