The Ark Files - Gotcha Covered

Some like it hot

To keep itself warm, an animal depends on its fur to trap warm air close to the body. Some animals such as the Antarctic Fur Seal, that live in really cold climates, have a double fur coat: an outer one of long, straight hair and an inner one of short, curly, woolly fur. A Polar Bear's coat is not only very long but the hairs are also very oily, and this keeps out the freezing water when the bear takes an icy, shallow dip. Diving and swimming at depths however, causes the fur to get really wet and to lose its warmth as the trapped air bubbles are driven out by the water pressure. Blubber under the skin compensates for this. In Arctic seals, this blubber is so efficient that they start to pant when the temperature reaches a mere 10°C!

Feathers as doonas

Feathers are better than fur at keeping an animal warm. Downy ones are perfectly designed to trap warm air. Chickadees, redpolls and creepers are tiny birds which survive quite well in a northern Arctic winter, despite having a body mass of only 10 grams and with no blubber in sight!

Penguins have developed special feather coats. Their feathers are very long and soft and angled close to the body with fluffy tufts at their bases which mat together to form a layer that is virtually impenetrable to wind or water. This feather coat covers more of their body than any other living bird. It goes right down over their legs and toes and even onto the beaks of the little Adelie Penguin.

Some like it cool

You wouldn't think that a fur coat could help in the desert but the thick, hairy coat of a camel, which covers its upper body, shields it from the sun. Most of the sun's rays that strike a camel's back never reach the skin. Fur surface temperatures on the back of a camel can reach 70-80°C, while the camel's skin temperature beneath is only about 40°C. Below this, a camel's legs and belly are nearly naked. They lose accumulated heat through these thin surfaces by crouching on the night-cooled sand to sleep.

Kangaroos also have rather thick fur over most of their bodies except their arms. During hot weather they lick the skin of their arms and the evaporating moisture helps to keep them cool.

Feathers as water bottles

The belly feathers of sand grouse in the African desert have a unique structure. They can act as a sponge to trap water. The male can carry water to his young after first soaking himself in a water hole. The thirsty chicks rush to him and, seizing his wet belly feathers in their beaks, strip the water from them with downward jerks.

To oil, or not to oil?

Most water birds have a large oil gland at the base of the tail. The bird takes the oil in its beak and works it through the feathers so that they are kept water repellent. The water drops simply roll off their back.

Cormorants and darters however, are different: they do not have oil. This is just as well, for their feathers become water-logged when they swim, and this helps them to dive in search of fish. Afterwards they have to stand on the rocks and hold their wings out to dry.

Coats of arms

Anteaters use coats as a defence. Their body is covered with coarse, bristly hair which protects them from the bites of thousands of angry termite soldiers.

When the hair on an animal's neck and back stands up, it is a "watch out" sign of aggression. Wolves and wild cats, and even domestic cats and dogs, raise their hackles. Lions and Barbary Sheep have a heavy mane of hair behind their heads and around their necks to increase their size and presence and for added protection when fighting.

Then there is the coat of armour of echidnas, hedgehogs and porcupines which is made up of extremely sharp spines. When these animals are threatened they roll up into a prickly ball, giving the recognised signal to the animal world of "Come any closer and you'll get spiked!"

Coats of many colours

Some animals like to be seen. Monkeys have some of the most spectacularly coloured coats of all mammals. Because their colour vision is so good they use colour to recognise each other and to communicate.

The De Brazza's Guenon of Africa has a white beard, blue spectacles, orange forehead and a black cap. The Mandrill has a scarlet and blue face and his other end is just as bright - he has a red and blue striped bottom! Whether he is coming or going you can't miss him!

And what about we humans? Well, calling someone a "hairy ape" may not be such an insult. Chimpanzees and humans have the same number of hairs on their bodies. Chimps' hair tends to be longer and blacker, but we are just as hairy.