Bird skeleton: features of the structure

In the article we will talk about what are the features of the structure of birds, what is their skeleton. Birds are interesting because the only group of vertebrates (except bats), capable not only of floating in the air, but of a real flight. Their structure is well adapted for this purpose. As masters of the air, they perfectly feel on the ground and on the water, and some of them, ducks for example, - in all three environments. In this role plays not only the skeleton of the bird, but also feathers. The main event that ensured these creatures prosperity was the development of their plumage. Therefore, we will consider not only the skeleton of a bird, but briefly tell about it.

Like wool in mammals, the feathers first arose as a heat-insulating cover. Only a little later they were transformed into bearing planes. Birds were dressed in feathers, apparently for millions of years before they acquired the ability to fly.

Evolutionary changes in the structure of birds

Adaptation to flight led to the restructuring of all systems of organs and behavior. Changed and the skeleton of the bird. The photo shown above is an image of the internal structure of the pigeon. Structural changes are manifested mainly in the increase in muscle strength with a decrease in body weight. The bones of the skeleton became hollow or cellular or were transformed into thin curved plates, while retaining sufficient strength to perform the functions assigned to them. Heavy teeth have been replaced by a light beak, but the feather cover is an example of lightness, although it can weigh more than a skeleton. Between the internal organs are located the breathing air bags.

Features of the pigeon skeleton

We offer a detailed look at the skeleton of a pigeon. It consists of pelvic bones, wing bones , caudal vertebrae, trunk, cervical region and cranium. In the skull, the back, head, forehead, beak and very large eye sockets are distinguished. The beak is divided into 2 parts - upper and lower. They move apart from each other. The cervical region includes the base of the neck, throat and neck. The skeleton of the pigeon in the dorsal part consists of sacral, lumbar and thoracic vertebrae. Chest - from the sternum, as well as 7 pairs of ribs attached to the thoracic vertebrae. The caudal vertebrae are flattened and attached by discs consisting of connective tissue. This, in general terms, is the skeleton of a bird. Its scheme was presented above.

Bone Skeleton Transformation

The transformation of the skeleton associated with the movement of birds in the hind limbs and the use of the forelegs for flight is particularly evident in the shoulder and pelvic belts. The shoulder girdle is rigidly connected to the sternum, and therefore when flying, the body hangs on its wings. This is due to the greatly expanded coracoid bones, which are absent in mammals.

The bird's skeleton has a markedly strengthened pelvic girdle. The hind legs keep these animals well on the ground (on the branches when climbing or on water when swimming) and, what is especially important, successfully shots blows at the moment of landing. As the bones became thin, their strength increased as a result of intergrowth with each other, when the structure of the skeleton of the bird changed. As in mammals, three paired pelvic bones merged with the spine and between themselves. There was a merging of the trunk vertebrae, beginning from the last thoracic vertebra and ending with the first caudal vertebra. They all became part of a complex sacrum, which strengthened the pelvic girdle, allowing the limbs of birds to perform their functions without disturbing the work of other systems.

The finiteness of birds

You should also consider the limbs, characterizing the structure of the skeleton of the bird. They are strongly modified in comparison with the typical features characteristic of vertebrates. Thus, the bones of the metatarsus and tarsus elongated and merged, forming an additional segment of the limb. The thigh is usually hidden under the feathers. The hind limbs have a mechanism that allows the birds to rest on the branches. The muscle flexors of the fingers lie above the knee. Their long tendons pass along the front side of the knee, then along the back side of the forging and the lower surface of the fingers. When bending fingers, when a bird grabs a branch, the tendon mechanism locks them, so that the grip does not fade even during sleep. In its structure, the hindlimb of the bird is very similar to the leg of a man, but many of the bones of the lower leg and the feet are fused.

Brush

Characterizing the features of the skeleton of birds, we note that especially sharp changes in connection with adaptation to the flight occurred in the structure of the brush. The remaining bones of the forelegs fused, forming a support for the primary mahovye feathers. The retained first finger is the support for the rudimentary winglet, which acts as a special regulator, reducing the braking of the wing at low flight speeds. Secondary flight feathers are attached to the ulnar bone. Together with the remarkable arrangement of the feathers themselves, all this creates a wing - an organ that is characterized by high efficiency and adaptive plasticity. Below is the skeleton of a dodo bird extinct in the 17th century .

Wings

Lifting power and flight control are provided by flight and tail feathers, but their aerodynamic properties are not yet fully understood. At normal waving flight wings move downwards and forward, and then - sharply upwards and backwards. When struck downward, the wing has such a steep angle of attack that it would extinguish the speed if the primary fly feathers did not act at this time as an independent supporting plane that prevents braking. Each pen rotates up and down along the rod, so that a forward thrust is created, which is facilitated by the separation of their ends. In addition, at a certain angle of attack, the winglet is diverted from the front of the wing. In this way a cut is formed, which reduces turbulence over the bearing plane and thereby suppresses inhibition. When landing, the bird extinguishes the speed beforehand, placing the body in a vertical plane, pulling back the tail and braking its wings.

Features of the structure of the wings of various birds

Birds, who can fly slowly, have particularly well-marked gaps between the primary mahovies. For example, in the golden eagle (Aquilachysaetos, pictured above), the intervals between the feathers amount to 40% of the total wing area. In vultures, a very wide tail creates an additional lifting force when hovering. The other extreme as compared with the wings of eagles and vultures form the long and narrow wings of seabirds.

For example, albatrosses (a photo of one of them is presented above) almost do not wave their wings, hovering in the wind and then diving, then abruptly soaring up. Their way of flight is so specialized that in calm weather they are literally chained to the ground. The wings of the hummingbirds bear only primary feathers and can perform more than 50 strokes per second when the bird hangs in the air; While they move back and forth in the horizontal plane.

Fenestrain

The feather cover is adapted to perform a variety of functions. Thus, rigid flight and tail feathers form wings and tail. A covering and contour give the body a streamlined shape, and fluff is a thermal insulator. Laying on each other like tiles, feathers create an uninterrupted smooth covering. The finer structure of the pen, to a greater extent than any other anatomical features, provides the birds with prosperity in the air. Each of them has a plague of hundreds of beards, located in the same plane on both sides of the rod, and from them also the beardlets that carry hooks from the side removed from the body of the bird also leave in both directions. These hooks cling to the smooth beards of the previous row of barbs, which allows to keep the shape of the fan unchanged. On each mahovogo pere of a large poultry there are up to 1.5 million beards.

Beak and its meaning

The beak serves the birds as a manipulative organ. Using the example of a woodcock (Scolopaxrusticola, one of which is shown in the photo above), one can see how complex the beak's actions can be when the bird plunges it into the soil while hunting for the worm. Having stumbled upon prey, the bird by the contraction of the corresponding muscles shifts forward the square bones that make up the jawbone. Those in turn push the zygomatic bones forward , which cause the tip of the supra-limb to bend upward, there is an oval hole through which the tendon of the subclavian muscle passes, attached to the upper side of the shoulder. Thus, with the contraction of the subclavian muscle, the wing rises, and when the pectoralis contract, it descends.

So, we outlined the main features of the structure of the skeleton of birds. We hope you have discovered something new about these amazing creatures.