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The cat righting reflex is a cat's innate ability to orient itself as it falls in order to land on its feet. The righting reflex begins to appear at 3–4 weeks of age, and is perfected at 6–7 weeks. Cats are able to do this because they have an unusually flexible backbone and no functional clavicle (collarbone). The minimum height required for this to occur in most cats (safely) would be around . Cats without a tail also have this ability, since a cat mostly moves its hind legs and relies on conservation of angular momentum to set up for landing, and the tail is in fact little used for this feat. ==Technique== After determining down from up visually or with their vestibular apparatus (in the inner ear), cats manage to twist themselves to face downward without ever changing their net angular momentum. They are able to accomplish this with these key steps: #Bend in the middle so that the front half of their body rotates about a different axis from the rear half. #Tuck their front legs in to reduce the moment of inertia of the front half of their body and extend their rear legs to increase the moment of inertia of the rear half of their body so that they can rotate their front further (as much as 90°) while the rear half rotates in the opposite direction less (as little as 10°). #Extend their front legs and tuck their rear legs so that they can rotate their rear half further while their front half rotates in the opposite direction less. Depending on the cat's flexibility and initial angular momentum, if any, the cat may need to perform steps two and three repeatedly in order to complete a full 180° rotation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cat righting reflex」の詳細全文を読む スポンサード リンク
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