爲什麼鱷魚睜一隻眼睡覺？
Why Crafty Crocodiles May Be Sleeping With One Eye Open
爲什麼鱷魚睜一隻眼睡覺？
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.
對人類來說，“睡覺睜一隻眼”只是對要“提高警惕”的一個比喻；但是對某些動物來說卻是一種習性。一半大腦處於休息狀態，另一半大腦時刻保持警惕，這種現象被稱爲“半腦睡眠”。
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.
科學家相信，這種在海豚海獅等海洋哺乳動物和多數鳥類身上存在的天賦，實際上有很多用途。鳥兒睡眠時一隻眼保持警惕是爲了免受捕食者傷害，海豚卻是爲了看護自己的幼崽。很多羣居動物也用此技能來保持對身邊任何有趣活動的關注。
Now researchers from Australia's 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 University's 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.
澳大利亞La Trobe大學的研究者發現，鱷魚似乎也進化了出此技能。他們在大學水族館騰出地方，圈禁了3條幼年鹹水鱷並監控它們的表現。他們發現，在無外界打擾的情況下，這些爬行動物只有不到一小時睜一隻眼閉一隻眼。似乎大多數時間裏，它們跟人類一樣，是緊閉雙眼睡覺的。
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，當研究者們加入了干擾，情況立刻轉變了。他們加了一隻新鱷魚進入圍欄。雖然都是同類，其他鱷魚還是立刻進入警戒狀態。它們開始針對這個新來的鱷魚，更久地保持一隻眼睜着。
If the tests are positive, it would indicate that birds, mammals and reptiles all display this behavior. The only ones that don't? 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!
如果實驗有效，我們可能會獲得鳥類、哺乳動物和爬行動物都有此行爲的結論。什麼動物例外呢？陸地動物和人類睡覺時，才需要雙眼緊閉。Lesku表示，雖然我們認爲睜一隻眼閉一隻眼睡覺的動物奇怪，但其實這種行爲才最正常不過。
譯文屬原創，未經允許，不得轉載。
