关于海豚，8个令人难以置信的事实
Dolphins never cease to amaze. As researchers delve into the underwater world of these brilliant cetaceans, we're learning how full of surprises these creatures are, from their intricate social lives to their intelligence. Here are just some of the ways dolphins are exceptional, both physically and mentally.
海豚总是让人惊叹不已。当研究人员深入水下世界研究这些聪明的鲸类动物时，我们了解到这些生物是多么令人惊奇，从它们复杂的社会生活到它们的智力。这里列出海豚在身体和精神上的一些特殊之处。
1. Dolphins evolved from land-based animals
海豚是从陆生动物进化而来的
(Photo: Matt9122/Shutterstock)
Dolphins didn't always live in the water. Millions of years ago, the ancestors of dolphins roamed across land. The dolphins we know today are evolved from even-toed ungulates, which had hoof-like toes at the end of each foot. But around 50 million years ago, these ancestor animals decided the ocean was a better place to be. They eventually returned to the water and evolved into the dolphins that we know today.
海豚并不总是生活在水里。数百万年前，海豚的祖先在陆地上游荡，我们今天所知道的海豚是由偶蹄类动物进化而来的，偶蹄类动物在每只脚的末端都有类似蹄的脚趾，但是大约在5000万年前，这些祖先知道了海洋是一个更好的地方。它们最终回到了水中，进化成了我们今天所知道的海豚。
2. Dolphins stay awake for weeks on end
海豚连续几周保持醒着的状态
(Photo: Jman78/iStockPhoto)
Recent research has shown the surprising capabilities of dolphins for staying awake for days or weeks on end — or possibly indefinitely.
最近的研究显示，海豚有惊人的能力连续几天或几周保持清醒，甚至可能是无限期的。
On the one hand, the ability makes perfect sense. Dolphins need to go to the ocean's surface to breathe, so they can't simply breathe automatically like humans do. They have to stay constantly awake to take a breath and avoid drowning. How do they do this? By resting just one half of their brain at a time, a process called unihemispheric sleep.
一方面，这种能力非常有意义。海豚需要到海洋表面呼吸，所以它们不能像人类那样简单地自动呼吸。他们必须时刻保持清醒来呼吸，避免溺水。他们是怎么做到的?它们一次只休息大脑的一半，这一过程被称为大脑半球睡眠。
3. Dolphins can't chew
海豚不能咀嚼
(Photo: Alicia Chelini/Shutterstock)
If you've ever watched a dolphin eat, you've noticed that they seem to gulp down their food. That's because dolphins can't chew. Instead, their teeth are used to grip prey. Sometimes, they'll shake it or rub it on the ocean floor to tear it into more manageable pieces. One theory for why they've evolved to do away with chewing is because they need to quickly consume fish before it can swim away. Skipping the process of chewing ensures their meal doesn't escape.
如果你曾经看过海豚吃东西，你会注意到它们似乎会狼吞虎咽，那是因为海豚不能咀嚼。相反，它们的牙齿是用来抓住猎物的。有时，它们会在海底摇晃或摩擦猎物，把它撕成更容易处理的碎片。有一种理论解释了它们进化到不再咀嚼的原因，那就是它们需要在鱼游走之前迅速吃掉它们，跳过咀嚼的过程确保他们的食物不会逃脱。
4. Dolphins have worked for the Navy since the 1960s
海豚自20世纪60年代以来一直为海军工作
(Photo: U.S. Navy photo by Photographer's Mate 1st Class Brien Aho/Wikimedia Commons)
The idea of dolphins being employed by the military to scan harbors for enemy swimmers or pinpoint the location of underwater mines may seem like the plot of a movie, but it's true and has been for decades.
海豚被军方用来扫描港口，寻找敌方潜入者，或者精确定位水下水雷的位置，这种想法可能看起来像是电影的情节，但这是真的，几十年来一直如此。
5. Dolphins teach their young how to use tools
海豚教它们的幼崽如何使用工具
(Photo: Joost van Uffelen/Shutterstock)
A 2005 study by researchers revealed that a population of dolphins living in Shark Bay, Australia, use tools, and they pass that knowledge down from mother to daughter.
2005年，研究人员的一项研究显示，生活在澳大利亚鲨鱼湾的海豚种群使用工具，并由“父母”将这些知识传给“儿女”。
6. Dolphins form friendships through shared interests
海豚通过共同的兴趣建立友谊
This particular group of dolphins have been keeping researchers busy over the years, revealing information about group's culture and social habits.
多年来，这群海豚一直让研究人员忙得不可开交，它们揭示了群体文化和社会习惯的信息。
7. Dolphins call each other by name
海豚互相叫名字
We've know dolphins communicate, but this is new: Dolphins have names and respond when called. Dolphins within pods have their own "signature whistle," just like a name, and other dolphins can use that special whistle to get the attention of their pod mates. Considering dolphins are a highly social species with the need to stay in touch over distances and coordinate together, it makes sense they would have evolved to use "names" much in the same way people do.
我们知道海豚会交流，但不知道的是：海豚有名字，当别人叫它们的时候它们会回应。圆荚体中的海豚有自己的“标志性哨声”，就像名字一样，其他海豚可以用这种特殊的哨声来吸引圆荚体同伴的注意。考虑到海豚是高度群居的物种，需要保持远距离的联系和协调，它们进化到与人类非常相似地使用“名字”的方式是有道理的。
8. Dolphins get high on fish toxins
海豚对鱼的毒素很敏感
We know that pufferfish have strong toxins. Apparently dolphins
know this too, and they use this for recreational benefit.
我们知道河豚鱼有很强的毒素。显然海豚也知道这一点，而且它们用这个来娱乐。
