7．Great white sharks in the Pacific Ocean．Wildebeest（角马） in Africa．Arctic terns（北极燕鸥） in the Atlantic．At first，these animals seem quite different．One swims，one walks，and the other flies．But they all have one thing in common．They all migrate（迁徙）．
Some migrating animals move to a place with a better temperature．Some go to find food or water．The groups travel as one，but during the trip，they face many different challenges．
One challenge is distance．Some migrating animals take very long trips．For example，one great white shark swam from Australia to South Africa and back．In nine months，it swam about 20，000kilometers!
Another challenge is finding enough food and water during the journey．For example，each Mali elephant needs over 200liters of water each day．To get this，they need to go from one waterhole to another．
Besides，migrating animals have to keep away from other animals that want to eat them．The zebra （ 斑马） has to avoid lions．Traveling as a group helps keep them safe．When one zebra is in trouble，the other members make a circle around it．
By working as a group，migrating animals travel to live better lives．
根据短文内窖．完成下面的思维图．（每空词数不限）
86．better 87．food or water88．shark89．enough90．keep away from．
