Giraffes are hard to miss. In zoos or in their natural habitat - Central Africa - they rise above the rest of the animals. Still would! After all, the giraffe is the tallest land animal on the planet. The length of the giraffe's neck has puzzled nature researchers for many years. One often hears: "Where did they get such a long neck?"
Looking at how the three-meter (not counting the neck!) Animal stretches out its neck, the length of which is 2.5 meters, and then sticks out its tongue another thirty centimeters long, reaching the seemingly unattainable branch of acacia, one might think that the giraffes have "grown" themselves such a long neck as a result of long exercise. But is a giraffe really capable of somehow affecting its own growth? Doesn't a change in one trait affect the organism as a whole? Let's take a closer look at the giraffe ...
The giraffe is a mammal, and therefore, its anatomical structure should be very similar to that of other mammals. Like the vast majority of animals, the giraffe has seven cervical vertebrae. What if he didn't have these seven links between the shoulders and the base of the skull? The huge head of a giraffe must always be on top. When a giraffe is standing, almost half of its 225-kilogram neck musculature is in tension. And muscle mass is directly related to the number of joints it needs to support. If, for example, there were only two joints - on the skull and on the chest - the weight of the animal would be much less, and less energy would be required for its vital functions. And if the lack of food resulted in a change in the structure of the neck, would not this evolutionary process also change the number of cervical vertebrae and joints? Of course, the problem with such a design would be the loss of flexibility and a sharp weakening of resistance when hitting the head or neck.
In contrast, a neck with more joints would require more energy and more muscle mass. This would shift the center of gravity of the giraffe's body forward; consequently, the head would also be extended forward, and the hind legs would be lifted off the ground - of course, provided that the front legs were able to withstand this. So seven cervical vertebrae are an excellent constructive solution.
Due to the fact that the giraffe's head is so high, its huge heart must be able to supply a sufficient amount of oxygen-enriched blood to the brain (to a height of 3 meters). Given the high blood pressure, this could create serious problems when the giraffe tilts its head (say, at a watering hole), if not for the unique system of arteries with thickened walls, various valves, a network of tiny vessels (rete mirabile - "wonderful network") and receptors evaluating blood pressure. With their help, the blood flow in the giraffe's neck is regulated depending on the pressure. Even to those who consider this whole system only "adaptation to high pressure in the blood vessels", the giraffe seems to be a unique creature.
The giraffe has perhaps the strongest heart in the animal kingdom, because it needs blood pressure almost twice as high to raise blood up the neck to the brain. With this pressure, only very unusual structural features save the giraffe from hallucinations when he tilts his head at the watering hole.
Equally surprising is the fact that giraffe does not accumulate blood in the legs, and the giraffe does not bleed out after injuring the leg. The key to this secret lies in very strong skin and internal ligaments, which ensure the integrity of blood vessels and normal blood flow. The structure of the giraffe's skin has become the subject of intense research by NASA specialists in connection with the development of new space suits. In addition, all the arteries and veins in the giraffe's legs are very deep, and this also prevents bleeding. The capillaries approaching the surface of the skin are very small, and the red blood cells in a giraffe are three times smaller than in humans; due to this, they pass through narrow capillaries. Obviously, these unique features of the giraffe's anatomy are related to the length of its neck.
But that is not all. Small red blood cells have a relatively large surface, they better and faster absorb oxygen from the lungs. This helps to efficiently supply oxygen to both the limbs and the head.
The lungs work in harmony with the heart to provide oxygen to the tissues, but the giraffe is unique in this sense as well. Its lungs are eight times larger than that of a human, and its respiratory rate is three times less.
Such slow breathing is necessary so that when the huge masses of air move, the ribbed four-meter trachea does not weather. Why does a giraffe have such large lungs? After inhalation, no animal can physically exhale completely. The problem of the giraffe is complicated by the fact that due to the long trachea, a very large volume of "dead space" air is formed - more than a person can inhale at a time. To compensate for this, it is necessary to increase the volume of the lungs - then the air of the "dead space" will make up a small part of the total air in the respiratory tract. And in the body of a giraffe this physical problem has been successfully solved.
The miracle of the birth of a giraffe bears the indelible stamp of intelligent design. A newborn is born, falling from a height of one and a half meters, since the mother cannot sit on bent legs, and to lie on the ground means inevitably to become the prey of a lion or other predator. Moreover, the cub's head, like that of other animals, is disproportionately large, which complicates childbirth. But the main thing is that this head is connected to the 70-kilogram body through a fragile long neck. And if the newborn falls head first, then when the body falls from above, the baby will inevitably break its neck; and if the body is forward, then it will still break the neck under the weight of the body's weight, when it has already come out, but the head is not yet. However, there is a way out of this position: the newborn giraffe has very narrow hips of the hind legs, and the neck is long enough so that the head runs along the body to the hips. Thus, first the hind legs come out, the newborn rests on them, while his head is supported by the hips, and the neck, due to the extreme flexibility, remains intact.
Such a miracle becomes possible only with a combination of strictly defined structural features and just such a neck length. A few minutes later, the newborn is already standing in a graceful position between the mother's legs. In the four years from birth to maturity, the giraffe's neck grows from one-sixth to one-third of the animal's total height. Thanks to this feature, the giraffe quickly gets the opportunity to bend towards the water while standing on long legs. In the very first year of life, a young giraffe feeds almost exclusively on mother's milk, and this is not difficult.
From an ecological point of view, the giraffe fits perfectly into the environment. Fast growing trees create too much shade and thus destroy the grass that serves as food for other savannah animals, so such trees must be "trimmed". In addition, herbivores need a "sentry" who will be able to see silently creeping felines in the tall grass. The giraffe is perfect for this role, not only because of its height, but also because of its excellent eyesight and behavior. Having warned other animals about the threat with several waves of its tail, it fearlessly goes out to meet the danger. Huge growth, strong skin, lethal force of impact of hind hooves and rapid gait make an adult giraffe a very unattractive prey for any predator.