Elephants are often referred to as pachyderms. However, their skin is so sensitive that they can even get sunburnt. That's why elephants often cover themselves with several layers of mud. This also acts as a pleasant cooling pack against the scorching heat. With their large ears, elephants cannot hear any better than other animals, but they help them to cope with the African heat. When they fan their ears, the blood in them cools down and provides refreshment. African elephant babies grow in their mother's womb for 20 to 22 months before they see the light of day. This means that elephant cows have the longest gestation period of all mammals. An elephant herd often consists of ten to twelve animals and is led by an experienced cow.