The giraffe Giraffa camelopardalis
Obviously, describing giraffes does not seem to make a sense – all of us have known about this tallest living land animal from our early childhood. Let’s just learn some facts about giraffes. Fully grown male giraffes reach the height of 5.5 m, and weigh up to 900 kilograms. Each individual giraffe has a unique coat pattern, as people have individual fingerprints.
Giraffes have two horns on the sides of their heads covered with skin and fur and thickened on top. Their beautiful black eyes are laced with thick eyelashes. These graceful animals have acute eyesight, good hearing and developed sense of smell which all help them to spot predators at a distance. Their height allows giraffes a great vision of the wide range. It is interesting that despite its extremely long neck, which makes it possible for the giraffe to pick up leaves from very tall trees, it has just seven vertebrae like all other mammals – though each cervical vertebra is over 25 cm long. Apart from elongated neck, giraffes have very long tongues with the length of 45 cm, and they use their tongue and prehensile lips to reach around the thorns while picking the leaves and sprouts. Giraffe legs are very long and strong too; their step distance may reach 6 to 8 meters, and they can run at a speed of 60 km/h. Adult giraffes are capable of killing a large carnivore, including lions, with deadly blow of their front hooves.
The giraffe great height creates some problems for this animal. Its heart must generate a very high blood pressure to maintain blood flow to the brain that is located 3.5 m higher than the heart. That is why giraffe heart is very large and strong: it can weigh 12 kg and have the length of 60 cm; the wall of the heart can be as thick as 6 cm, and it creates the blood pressure of 340/230 mm Hg. Such a high pressure is associated with the risk of haemorrhages, but giraffes have several adaptations for solving this problem: their skin and connective tissues are thick and tight, and the capillaries in the surface areas of the skin are very thin. To move through the narrow capillaries, the giraffe erythrocytes are very small though they have a large surface area. Giraffe jugular arteries and veins have special system of valves to prevent excess blood flow into the brain when the giraffe lowers its head (for instance, when it is drinking); the valves also prevent blood flow back to the heart, which otherwise could cause oxygen deficiency in the brain. Gestation in giraffe females lasts over 14 months and results in the birth of a single calf. The newborn calf weighing about 50 kilograms drops on the ground from the height of almost two meters. The mother urgently licks her baby’s body over, and the calf raises its head after ten minutes. After another 45 minutes little giraffe is standing on its legs and it can run around in a few hours. In the first few days the calf stays in the clearings, hiding in the thickets, with its patchy coat pattern providing a perfect camouflage, blending with shadows and leaves. After some time, the mother and her baby join her family group. In the first months of the calf’s life the mother leaves her youngster together with other calves in a "nursery", where calves play together while their mothers go out to forage.
