Animals will make extraordinary and often mysterious expeditions to find a good meal, sexy mates, and the perfect place to raise a family. This month, billions of cicadas will burst out from their 17-year-old hiding places to complete one of the longer journeys in time, while moving only a few inches from burrow to daylight. Other migrations cover thousands of miles.

　　当人类因为生活而搭乘飞机、火车从一个城市迁徙到另一个城市的时候，动物们也在神秘远征，它们同样也是为了获得美餐、佳人和完美的安家场所。它们的路途是那么艰辛，以至随时都有丧命的危险。这个月，数亿只蝉将告别它们居住17年之久隐居地，完成生命旅程。它们一天的行走距离只有几英寸。其它的迁徙将长达数千公里。以下是生活科学网站评出的十大最难以置信的动物旅行。

10、Humpback Whales　　迁徙距离最长的座头鲸

　　Humpback whales hold the world's record for longest mammalian voyage. One population spends the warmer months eating a literal ton of food a day in waters off the Arctic Peninsula. Come wintertime, they swim 5,000 miles away to balmy breeding grounds near Columbia and the Equator.

　　座头鲸保持着世界上哺乳动物中迁徙距离最长的记录。在气候较暖的几个月里，一头座头鲸每天会在北冰洋附近海域吃掉大约1吨的食物。而到了冬天，它们又会游行5000英里，到达哥伦比亚和赤道附近的温暖海域觅食。

9、Freshwater Eels　　适应不同盐度的淡水鳗

　　Freshwater eels are born prepared for the rough waters they face in life. After hatching in the salty Sargasso Sea, the eels swim to freshwater rivers in the United Kingdom and the East Coast of North America. On the way, their kidneys adapt to the change in salinity. When it's time to lay eggs, the eels and their kidneys will return to their beginnings.

　　淡水鳗往往一出生就将面对一段最恶劣的水域生涯。在北大西洋西印度群岛附近的马尾藻海的咸水当中出生后，它们会游往英国和北美洲东海岸的一些淡水河流当中。在这个迁徙的过程中，它们的肾脏会适应水中盐度的不同变化。而当它们要产卵的时候，它们又会回到海水当中，而它们的肾脏又会发生变化来适应海水的高盐度。