Les moustaches est un instrument de mesure, mais c'est la structure particulière du corps du chat qui permet ce genre d'acrobatie...
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Whiskers help the cat feel his way around. Whiskers are so sensitive that they can detect the slightest directional change in a breeze. At night, for example, this helps a cat slink its way through a room and not bump into anything. How? The air currents in the room change depending on where pieces of furniture are located. As the cat walks through the room and approaches the couch, he'll know which direction to turn based on the change in air current around the couch.
In addition to having sensory properties, a cat's whiskers are also a good indicator of his mood. When a cat is angry or feels defensive, the whiskers will be pulled back. Otherwise, when the cat is happy, curious or content, the whiskers will be more relaxed and pushed forward.
But the whisker's primary use is to help a cat judge whether or not he'll fit through an opening. A cat's whiskers are roughly as wide as his body -- sort of a natural ruler. The whisker tips are sensitive to pressure. You'll probably see a cat stick his head in and out of an opening before he puts his body in. He's judging the width of the opening, and is determining if he can fit into it. An interesting note: cats don't have a true collar bone, like humans. This allows them to turn and twist their way through very narrow openings.
http://animals.howstuffworks.c(...)2.htm
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Cats are so flexible because of their high number of vertebrae, or individual spinal bone disks. Including their tails, cats have up to 53 vertebrae. By comparison, a human spine contains 33 vertebrae. While all animals' vertebrae has cushioning between the individual disks, a cat’s spine has more elastic cushioning than most mammals. This allows them to be able to twist themselves more easily, at angles of as much as 180 degrees. Cats also have tiny collarbones, which gives them the ability to flatten themselves to fit through small openings. When cats fall from tall heights, their flexibility is what generally keeps them from breaking any bones, because they are able to twist and reposition themselves mid-fall to land on their feet.
http://www.wisegeek.com/why-ar(...)e.htm