Great white sharks2 are in the Pacific Ocean. Wildebeest3 are in Africa. Arctic4 terns5 are in the Atlantic6. At first， these animals seem completely different. One swims， one walks， and the other flies. But they all have one thing in common. They all migrate7.
　　大白鲨生活在太平洋。牛羚生活在非洲。北极燕鸥生活在大西洋。起初，这些动物似乎完全不同。大白鲨会游泳，牛羚会奔跑，而燕鸥则会飞翔。但他们都有一个共同点。他们都会迁徙。
　　Some migrating groups move to a place with a better temperature. Some go to find food or water. The groups travel as one， trying to survive. During the trip， they face many different challenges. One challenge is distance. Some migrating animals take very long trips. They go far away from their home areas. For example， one great white shark swam from Australia to South Africa and back. In nine months， it swam about 20，000 kilometers.
　　一些動物会以团体为单位迁徙到有更适宜温度的地方。一些则是去寻找食物或水。这些动物以群体活动是为了更好地生存。在旅途中，它们面临着许多不同的挑战。挑战之一是距离。一些迁徙的动物需要走很长的距离。它们远离自己的家乡。例如，一条大白鲨从澳大利亚游到南非，然后到了一定时间再游回去。在九个月内，它游了大约2万公里。
　　Another challenge is finding enough food and water during the journey. For example， each Mali elephant needs over 200 liters of water each day. To get this， they need to go from one waterhole to another.
　　另一个挑战是在旅途中需要找到足够的食物和水。例如，每一头马里象每天需要超过200公升的水。为了获取水，它们需要从一个水坑走到另一个。
　　In addition， migrating animals have to avoid other animals that want to eat them. For example， the zebra has to stay away from lions. Traveling as a group helps keep them safe. All the zebras in the group can watch for danger. When one zebra is in trouble， the other members make a circle around it.
　　此外，迁移的动物必须防范其他捕猎它们的动物。例如，斑马必须远离狮子。作为一个群体迁徙有助于保护它们的安全。所有的斑马都能警戒危险。当一只斑马处于困境时，其他的成员在它周围围成一圈保护它。
　　By working as a group， migrating animals can survive some of the world’s most extraordinary8 journeys.
　　作为一个群体一起迁徙，迁移的动物可以在这个世界上最非凡的旅程中更好地生存下去。