Nowhere else on Earth is seasonal change so extreme. 两极地区的季节变化非常极端
which tell others in the group that they must move on. 提醒蝗群中的其它成员它们应该动身了
There is no other species on the planet that responds as quickly and as dramatically to the good times as the desert locust. 好日子到来时 地球上没有其它物种 能像沙漠蝗那样迅速而又戏剧性地作出反应
Death Valley is the hottest place on Earth. 死亡谷是地球上最热的地方
but this herd concentrates on digging up the roots, 但这群象却忙着挖掘草根
the lions must travel great distances to find enough to live on. 狮子也必须长途跋涉 寻找生存所需的食物
So how on earth does a plant-eater this size survive in a place apparently totally devoid of vegetation? 那么在地球上 如此巨大的植食动物是如何 在这个寸草不生的地方生存的呢