Giraffe is the tallest land animal in the world, but one mystery, which baffles scientists, is how it got its long neck. A famous French zoologist Jean Baptist de Lamarck proposed a theory that at one time giraffe‘s neck was much shorter than what it is now. It had to raise its neck to eat the leaves of the trees. According to Lamarck, the part of the body, which is used most, develops most. The giraffe had to raise its neck time and again to reach the upper branches of trees when the leaves on lower branches were eaten away. This excessive use of the neck resulted in its gradual increase. The successive generations of the giraffe started having longer necks and finally today‘s long-necked giraffe emerged. The male giraffes grow up to a height of 5.5 metres and weigh more than 1,000 kilograms. It is herbivore and chews its food in spare time. The formation of giraffe’s body is such that its mouth can easily reach the leaves of high trees. Its tongue is about 45 centimetres long and constructed in such a way that it can eat even the leaves of thorny plants. It has a long upper lip that helps it wrench off many leaves at a time. The colour of giraffes resembles the shadow of the trees and as such it cannot be easily spotted by its enemies. It is usually yellowish-brown in colour and has highly sensitive ears. The giraffe’s ears can pick the faintest sounds, but it is nearly incapable of uttering sounds. The word ‘nearly‘ has been used because some of the female giraffes and their young ones have been found mooing like cow or ox in the zoological parks but most of them do not utter sounds. The reason for this inability lies in the underdevelopment of its voice box or larynx. Probably due to this reason, it has a keen sense of smell and sight. If attacked, it can run at a speed of 45 kilometres per hour for an extended period of time without getting tired. As far as fast running is concerned, it can beat even the fastest of horses. When some other animal attacks it, it retaliates with the help of its head and hind legs. As its eyes are far above the ground, it can easily see predators long before they can get close enough to attack. That is why even the lion has to be very cautious while attacking a giraffe. Lions always attack it from behind because giraffes strike with its head like a hammer.