In the article we will tell you about the featuresstructure 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.
Подобно шерсти у млекопитающих, перья возникли at first 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.
The adaptation to the flight led to a restructuringall systems of organs and behavior. Changed and the skeleton of the bird. The photo presented above is an image of the internal structure of the pigeon. Structural changes were manifested mainly in the increase in muscle strength with a decrease in body weight. The skeleton bones became hollow or cellular or transformed into thin curved plates, 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 Heavy teeth have been replaced by a light beak, but the feather cover is an example of lightness, although it can weigh more than a skeleton.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 breathing air bags.
We suggest to consider in detail 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 a 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. Such, in general terms, is the skeleton of a bird. Its scheme was presented above.
The transformation of the skeleton associated withthe walking of birds on the hind limbs and the use of the forelegs for flight, is especially evident in the shoulder and pelvic belts. The humeral girdle is rigidly connected with the sternum, and so when flying, the body hangs on its wings. This is due to the greatly expanded coracoid bones, which are absent in mammals.
Скелет птицы имеет заметно усиленный тазовый пояс.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 the 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. Like in mammals, three paired pelvic bones merged with the spine and between themselves. There was a merging of the trunk vertebrae, beginning with 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 extremities of birds to perform their functions without disturbing the work of other systems.
Следует рассмотреть и конечности, характеризуя bird skeleton structure. They are strongly modified in comparison with the typical features characteristic of vertebrates. Thus, the bones of the metatarsus and tarsus elongated and merged with each other, forming an additional segment of the limb. The hip is usually hidden under the feathers. A hind limb has a mechanism that allows birds to hold onto branches. The flexor muscles of the fingers lie above the knee. Their long tendons run along the front side of the knee, then along the back side of the pinhole and the underside of the fingers. When bending the fingers, when the bird embraces the branch, the tendon mechanism locks them, so that the grip does not weaken even during sleep. In its structure, the hind limb of a bird is very similar to the human leg, but many of the bones of the leg and foot have grown together.
Describing the characteristics of the skeleton of birds, we notethat especially dramatic changes in connection with the adaptation to flight occurred in the structure of the brush. The remaining bones of the forelimbs have grown together, forming a support for primary primary feathers. The surviving first finger is a support for a rudimentary wing, which acts as a special regulator that reduces wing braking at low flight speeds. Secondary wing feathers attached to the ulna. Together with the wonderful device of the feathers all this creates a wing - an organ characterized by high efficiency and adaptive plasticity. Below is the skeleton of the dodo bird, extinct in the 17th century.
Lifting and flight controlprovide primary and tail feathers, but their aerodynamic properties are not fully understood. In normal flapping flight, the wings move down and forward, and then sharply up and back. When struck down, the wing has such a steep angle of attack that it would dampen the speed if the primary fly feathers did not act at that time as an independent carrier plane that prevents inhibition. Each feather rotates up and down along the rod, so that a resultant forward thrust is created, aided by the opening of their ends. In addition, at a certain angle of attack, the wing is moved forward from the front of the wing. This forms a cut, which reduces turbulence over the carrier plane and thereby dampens inhibition. When landing, the bird pre-extinguishes the speed, positioning the body in a vertical plane, pushing the tail back and braking its wings.
Birds that can fly slowly havewell visible gaps between primary flywheels. For example, in the golden eagle (Aquilachysaetos, pictured above), the intervals between feathers make up 40% of the total area of the wing. At vultures, a very wide tail creates additional lift when hovering. The other extreme compared with the wings of eagles and vultures form long and narrow wings of seabirds.
For example, albatrosses (photo of one of thempresented above) almost do not flap their wings, hovering in the wind and then swooping down and then soaring steeply. Their flight mode is so specialized that in calm weather they are literally chained to the ground. Hummingbird wings carry only primary feathers and are capable of making more than 50 strokes per second when the bird hangs in the air; at the same time they move back and forth in a horizontal plane.
Перьевой покров приспособлен к выполнению diverse functions. Thus, hard fly and tail feathers form the wings and tail. And the covering and contour give the body of the bird a streamlined shape, and the down is a thermal insulator. Laying on each other like roof tiles, feathers create a continuous smooth cover. Thin structure of the pen to a greater extent than any other anatomical features, ensures the birds prosperity in the air. Each of them consists of hundreds of barbs, which are located in the same plane on both sides of the rod, and from them also go barbs on both sides, carrying hooks from the side remote from the body of the bird. These hooks cling to the smooth beards of the previous row of beards, which allows you to keep the shape of the fan unchanged. On each large feathering of a large bird there are up to 1.5 million barbats.
The beak serves birds as a manipulating organ.Using the example of a woodcock (Scolopaxrusticola, one of them is shown in the photo above), one can see how complicated the actions of the beak can be when the bird sinks it into the soil, hunting for a worm. Having stumbled upon the prey, the bird shifts the square bones, which are part of the maxillary arch, with contraction of the corresponding muscles. Those, in turn, push the zygomatic bones forward, which cause the tip of the mandible to bend upward, an oval opening through which the subclavian muscle tendon attaches to the upper side of the shoulder. Thus, with the contraction of the subclavian muscle, the wing rises, and with the contraction of the pectoral muscles - it drops.
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.
