Pourquoi certains animaux muent-ils ?

Chez certains animaux, notamment plusieurs espèces de reptiles, la mue, le remplacement de la peau, s'effectue.
Contrairement à nous autres, les humains, dont la peau est sans cesse renouvelée, chez certains reptiles (lézards ou encore serpents) , la peau est trop rigide, et bien que l'animal grandisse, la peau reste intacte.

Au bout d'un certain temps, la peau de l'animal ne suffit plus pour le "contenir" et se déchire.
L'animal en sort avec une peau plus grande, tout aussi rigide que la précédente, mais mieux adaptée à son évolution, et ainsi de suite.

A noter que la mue existe aussi pour certains crustacés, notamment les homards, qui ne sont pourtant pas des reptiles !

Complement internaute :
The present invention relates to a process for the production of a metal or semimetal hydride. More particularly, the present invention relates to a process for the production of a metal hydride, in which a metal or a semimetal which can form a metal or semimetal hydride, such as sodium, is reacted with hydrogen in a gas phase at a temperature which is within a temperature range of from 700xc2x0 to 1200xc2x0 C. in a reaction chamber which is equipped with a cooling device. The invention also relates to an apparatus for carrying out the process according to the invention, the apparatus comprising a reaction chamber which is equipped with a cooling device. Metal hydrides are known and are used for the separation of hydrogen. The hydrogen which is produced by a chemical or thermal method is separated in a high-purity form from a mixture which contains inert gases and/or noble gases, and from other gases which are also present in a gaseous state, and is then introduced into a metal or semimetal hydride.