Why Crafty Crocodiles May Be Sleeping With One Eye Open为什么鳄鱼睁一只眼睡？While for humans the expression sleep with one eye open is just a metaphor to keep alert, for some animals it is a way of life. Called unihemispheric sleep, it is the ability to snooze with one eye open and the corresponding half of the brain awake, while the other half rests.对人类来说，“睡睁一只眼”只是对要“提高警惕”的一个比喻；但是对某些动物来说毕竟一种习性。一半大脑正处于睡觉状态，另一半大脑时刻保持警惕，这种现象被称作“半脑睡眠中”。Researchers believe that this talent that has been observed in marine mammals like dolphins and seals as well as numerous bird species, serves many purposes. Birds use it to keep an eye out (literally) for predators while dolphins do it to keep track of their pods and young ones. Many social animals are also believed to use the technique to keep track of any interesting activities going on around them.科学家坚信，这种在海豚海狮等海洋哺乳动物和多数鸟类身上不存在的天赋，实质上有很多用途。

鸟儿睡眠中时一只眼保持警惕是为了免遭捕食者损害，海豚毕竟为了照料自己的幼崽。很多群居动物也用此技能来维持对身边任何有意思活动的注目。Now researchers from Australias La Trobe University have discovered that crocodiles may have also evolved this capability. The scientists began by placing three juvenile saltwater crocodiles inside a large enclosure at the Universitys aquarium and filming their behavior. They noticed that when left undisturbed, the reptiles spent less than an hour with one eye open. The crocodiles instead seemed to prefer snoozing with both eyes shut just like the rest of us.澳大利亚La Trobe大学的研究者找到，鳄鱼或许也演化了出此技能。

他们在大学水族馆留出地方，圈禁了3条幼年咸水鳄并监控它们的展现出。他们找到，在无外界睡觉的情况下，这些爬行动物只有将近一小时睁一只眼闭一只眼。

或许大多数时间里，它们跟人类一样，是关上双眼睡的。However, things changed drastically when the researchers introduced an external stimulus. They began by bringing a new young crocodile to the enclosure. Though it was one of their own, the other reptiles immediately appeared to perk up. The researchers noticed that the crocodiles slept with one open eye directly aimed at the newcomer, for longer amounts of time.然而，当研究者们重新加入了阻碍，情况马上改变了。他们特了一只新的鳄鱼转入围栏。虽然都是同类，其他鳄鱼还是马上转入警戒状态。

它们开始针对这个新来的鳄鱼，更久地维持一只眼睁着。If the tests are positive, it would indicate that birds, mammals and reptiles all display this behavior. The only ones that dont? Land-based animals and humans that need to fully shut down the brain and eyes for a snooze. Lesku says that while we have always called the one-eyed napping animals odd it may be that they are perfectly normal!如果实验有效地，我们可能会取得鸟类、哺乳动物和爬行动物都有此不道德的结论。什么动物值得注意呢？陆地动物和人类睡觉时，才必须双眼关上。

Lesku回应，虽然我们指出睁一只眼闭一只眼睡的动物怪异，但只不过这种不道德才最长时间不过。译文科香蕉英语原创，予以容许，不得刊登。

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