Most members of the bird class have mastered the terrestrial-air habitat. The adaptation of birds to flight is due to the peculiarities of their external and internal structure. This article will examine these aspects in more detail.
Signs of flight adaptation of birds
The main features that allow birds to master the air environment are:
- feather cover;
- modification of the forelimbs into wings;
- warm-bloodedness;
- light skeleton;
- the presence of a special bone - keel;
- double breathing;
- shortened intestines;
- the absence of one ovary in females;
- A well-developed nervous system.
These structural features illustrate how birds are adapted to flight.
Skeleton structure
With ease, it is possible to climb up for birds, first of all, thanks to the light skeleton. It is formed by bones, inside of which there are air cavities. The main sections of the skeleton of the birds are the skull, spine, belts of the upper and lower extremities and the free limbs themselves. Many bones are fused together, ensuring the strength of the entire "structure". A distinctive feature of the skeleton of birds is the presence of a keel. This is a special bone, to which the muscles that move the wings are attached. It is characteristic only for birds.
Integument
The features of adaptation of birds to flight are largely related to the features of the covers. Feathered are the only group of animals whose body is covered with feathers. They can be combined into three groups. The first is called "contour". Thanks to them, the body of the bird takes on a streamlined shape. Depending on the location on the body and the functions performed, the contour wings are coverts, flywheels and tail wings. They cover the body, forming the contours of the wings and tail. Regardless of the type, each wing consists of a central part - a rod, on most of which there are webs formed by first and second order barbs with hooks. The lower exposed portion of the pen is called ochin.
The second group is represented by feathers. Their beards are devoid of hooks, so the fan is not linked, but free. The third variety is fluff. A characteristic feature of its structure are fluffy beards, which are located in a beam at one end of a very shortened outskirts.
Using the plumage features as an example, it is easy to see how the birds adapted to flight. It provides thermoregulation, determines the color, the ability to move in airspace. By the way, the color of birds can serve as a disguise from predators, as well as one of the manifestations of demonstrative behavior.
Warmth
This adaptation of birds to flight is very important. Warm-bloodedness implies a constant body temperature that is independent of the environment. After all, as you know, with height the air temperature drops significantly. And if the birds were cold-blooded, like fish or amphibians, they would simply freeze during the flight. This feature is inherent in this group of organisms due to the progressive structure of the circulatory system. It is represented by a four-chamber heart and two circles of blood circulation. Therefore, venous and arterial blood do not mix, the exchange of gases and substances occurs very intensively.
External structure
The body of birds is divided into the following parts: head, movable neck, trunk, tail and limbs. On the head are eyes, nostrils and beak, covered with horn covers. Lack of teeth makes the skull even lighter. The eyelids in the eyes are motionless, the cornea is moisturized with the help of blinking membranes.
The main adaptation of birds to flight, certainly lies in the modification of the upper limbs. They are transformed into wings. Legs are lower limbs, often covered with horny scales. This feature of the structure remained in birds from their ancestors - reptiles. The claws on the toes help the birds stay on the supporting surface.
The internal structure of birds
The adaptation of birds to flight is also reflected in the structural features of most internal organs.
The digestive system is represented by the oral cavity, the esophagus, which forms the extension - goiter. In it, food undergoes additional enzymatic processing, becomes soft and is digested faster. Then the food enters the stomach, which consists of two sections: glandular and muscular, and then - into the intestine. It opens outward by a cesspool. The intestines of birds are shortened compared to other animals. Such a structure also makes their body lighter. Undigested food debris does not last long in the intestines and can be released through the cloaca even during flight.
The adaptation of birds to flight is also evident in the structure of the nervous system. Thanks to its development, animals have sufficiently clear color vision, which makes it easy to navigate in the air, even at a fairly high altitude. The hearing is also functioning well. And thanks to the developed cerebellum, coordination of movements is also at a high level . Birds react quickly during approaching danger or hunting.
Compactness is a characteristic feature of the reproductive system. Seed plants of males of small size, bean-shaped. They open their ducts directly into the cesspool. Females have only one ovary. This structure makes the weight of the birds significantly less. The ovum moves through the oviduct, where the fertilization process takes place, the egg is covered with shells and a calcareous shell. Further through the cesspool goes out.
Breathing features
The adaptations of birds to flight also concern the respiratory system. Indeed, for the intensive work of the muscular system, a continuous supply of oxygen to tissues and organs is necessary. Therefore, along with pulmonary breathing, birds have additional organs - air sacs. These are additional air tanks with a sufficiently large volume. Therefore, the breath of birds is also called double.
Habitat adaptation of birds
Features of the external structure often change depending on the habitat. For example, a woodpecker living in a forest has sharp claws. With their help, he moves along the branches of trees, leaning on a tail with hard feathers. The beak of this bird looks like a chisel. Using it, as well as using a long sticky tongue, he takes out insects and larvae from the bark, seeds from cones.
Birds - inhabitants of reservoirs, also have a number of important adaptations. These are short lower limbs with swimming membranes, a dense feather cover, smeared with water-repellent secretion of special glands. “Get out of the water” - this saying, known to everyone, appeared due to the features of the life of waterfowl.
Inhabitants of open spaces - steppes and deserts, have a protective color of feathers, very powerful legs and excellent eyesight.
The birds of the coast are the masters of the planning flight. Albatrosses, gulls and petrels are characterized by the presence of strong and long wings. But their tail is short. All this allows coastal inhabitants to fish directly from the air.
Is it possible to see prey at a distance of up to a thousand meters? For birds of prey, this is not a big deal. Falcon, hawk, eagle - bright representatives of this group. They have a large curved beak, which grab and tear food. And powerful sharp claws leave no chance of salvation. Predators are able to soar in the air for a long time thanks to their very wide wings. And those who hunt at night additionally have sharp eyesight and perfect hearing. For example, owls and owls.
Do all birds fly
Not all members of this class are able to fly. For example, penguins are excellent swimmers, their upper limbs modified into flippers. But these birds do not know how to fly. They have a keel, but the heavy weight does not allow them to soar into the air. A thick fat layer and thick plumage are simply necessary for life in the harsh conditions of the north.
The ostrich squad combines emu, kiwi, cassowary, and nanda. These feathered keels are absent. And the inability to fly is compensated by a quick run. This skill saves birds in lowland Africa.
The vast majority of modern birds are perfectly adapted to flight and habitat. They live in the forest, on water bodies and their coasts, steppes and deserts.
Representatives of the bird class are striking in their diversity, are important in nature and human life, and the characteristic features of the structure determine the ability to fly.