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鸟儿站在树枝上睡觉,为什么不会掉下来?
为什么鸟儿站在树上睡觉不会掉下来呢?这与鸟类特殊的腿部结构有关。鸟类蹲下时,它会拉伸与脚趾相连的肌腱,带动脚趾合拢。所以鸟儿在睡觉时, 它的爪子会毫不费力地弯曲并紧紧抓住树枝,直到腿部伸直,爪子才会松开。
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