56 The African Elephant

The elephant is the largest of all land animals. It can reach a height of eleven feet and weigh nearly six tons. The African elephant can also boast the biggest ears in the world. They can grow as large as three-and-a-half feet across. You might think that a gigantic animal like the elephant wouldn’t have much to worry about, but it has its problems too. And its huge ears can help it to deal with many problems ranging from pesky insects to great danger.

The ears are very effective fans that can be used to swat flies. The elephants’ huge ears also help them hear everything that’s happening nearby. A mother elephant might hear the approach of a dangerous lion that would kill her calves.

The elephants’ great size can sometimes present a heat problem. The larger an object, the harder it is for it to lose heat. Elephants live on the hot plains of Africa, where keeping cool is not an easy task. Elephants’ huge ears help them cool their bodies so they can survive in the heat. The large surfaces of the ears have many blood vessels that are very close to the surface of the skin. Blood that is closer to the surface cools more easily.

The most impressive use of the ears, though, is seen in an elephant’s threat display. When trying to threaten another animal, the elephant bellows and charges with both ears spread wide. This makes the huge beast look almost twice as large as it really is. Few enemies would dare to stand up to anything that colossal.

# 56 The African Elephant

大象是所有陆地动物中体型最大的。它的身高可达11英尺，体重接近6吨。非洲象还拥有世界上最大的耳朵，能长到3.5英尺宽。你可能觉得像大象这样的巨型动物没什么好担心的，但它也有自己的麻烦。而它巨大的耳朵能帮它应对从讨厌的昆虫到重大危险等诸多问题。

大象的耳朵是非常有效的“扇子”，可以用来驱赶苍蝇。它们巨大的耳朵还能帮它们听清附近发生的一切。母象或许能听到危险狮子的靠近——这种狮子会捕杀它的幼崽。

大象庞大的体型有时会带来散热问题。物体越大，散热就越困难。大象生活在非洲炎热的平原上，保持凉爽可不是件容易的事。大象巨大的耳朵能帮它们给身体降温，让它们得以在酷热中存活。耳朵的大面积皮肤上有许多靠近表层的血管，靠近表层的血液更容易冷却。

不过，耳朵最令人印象深刻的用途体现在大象的威慑展示中。当试图威慑其他动物时，大象会吼叫着冲过去，同时把两只耳朵完全展开。这会让这头巨兽看起来几乎是实际体型的两倍大，很少有敌人敢对抗如此庞大的家伙。