the Bird's kingdom
From time immemorial birds as any other live beings, drew a delighted look of the person. These finest creations meet practically everywhere - from polar ices to the noisy city centers.
Today our planet is occupied by billions the birds belonging to 9000 with superfluous kinds. All this infinite host is divided into 27 basic groups, or groups, and those, in turn, on 175 families.
the Bone skeleton
As a whole, the skeleton of a bird is constructed under the same basic scheme, as at the majority of others pozvonochnyh, but, thanks to a number of the features got during evolution, it is capable to maintain considerable loadings at flight. In the top part of a skeleton there is a short backbone with accrete together thick vertebras.
The Bottom part forms large grudinnaja a bone with kilevidnym a crest. In deepenings kilja to it powerful flying muscles fasten. At not flying birds kil completely is absent.
Extremely strong humeral belt with pair thin lopatochnyh bones is In front located. They are connected to a backbone and edges short kljuvovidno-kljuchichnymi sheaves. Wings are as though suspended on sharnirnyh joints, obrazuemyh kljuvovidnoj and kljuchichnoj by bones.
In front of a shovel are connected to a breast two kljuchichnymi the bones which bottom ends have grown together with a V-shaped plug. Such structure protects skeletal bones from the crises caused by powerful movements of flying muscles.
Behind a number accrete with tazovymi bones of vertebras forms difficult krestets to which finitenesses fasten. It enough prochen to bear blow at a landing, and on its wide surface there is enough place for fastening of foot muscles. Accrete tail vertebras are truncated, therefore tail feathers grow on limited enough site. Such structure provides efficient control a tail and, finally, with flight. The thorax is formed by edges, accrete with a backbone above and grudinnoj a bone below. On each edge there is a spur acting back, or krjuchkovidnyj a shoot, characteristic only for birds. These shoots are densely drawn to edges by sheaves and, coming the friend for the friend, are weaved into the strong skeleton similar to a basket.
All this design together with powerful grudinnoj a bone reliably protects an internal from damages. At auks diving deeply under water krjuchkovidnye shoots are very long and grasp not one, and at once two edges. Thanks to it the bird safely maintains pressure of water upon the big depths.
The Skeleton of a bird, at all its durability, at the same time is very easy. At the majority of kinds its weight does not exceed half or even one third of weight of feathers. To accrete bones superfluous sheaves and muscles are not required. Characteristic for others pozvonochnyh massive jaws and a teeth are lost as superfluous, the long tail is truncated, and in wings and paws much less bones, than in finitenesses of others pozvonochnyh. But the bird's neck in any way you will not name motionless. It consists of set of vertebras - from 13 at some songbirds to 25 at swans. For comparison: almost all vertebrate animals, including a giraffe, have more 7 cervical vertebras. The skull is connected to the top vertebra with the help sharnirnogo a joint which gives to a head where the big mobility, than at a mammal, and the circular review provides.
Transformations of finitenesses
Having undergone considerable changes, forward finitenesses of ancestors of birds in the course of evolution have turned to wings. However, humeral, beam and elbow bones of birds are quite comparable with ours, but pjastnye stones on a wing tip were transformed almost beyond recognition. From five fingers there were three, two of which are only slightly designated.
As huge flying muscles are located directly under wings, near to the center of gravity of a bird, to support in air balance for it not a problem. But feet are placed a little behind the center of gravity and consequently there is a question - why the bird "эх pecks эюёюь" standing on the earth?
The matter is that the femur hidden under plumage, unlike similar bones at the person or other mammals, is located along a trunk and connected to it several muscles. Thus, the knee joint is in the bottom end of a hip much is more subcentral weights, allowing to keep balance. It is an equivalent of our coxofemoral joint.
Two visible parts of the bird's paw at all have no analogues. The top part similar to our hip, actually is formed of accrete bones of a shin, and bottom - from accrete bottom stones of a shin and the top stones of foot. The joint located between them similar to a knee bent back, has no exact analogue in a skeleton of the person, but approximately corresponds to our anklebone.
Fingers on a paw no more than four (the fifth finger which is available for others pozvonochnyh, has disappeared at early stages of evolution). At some kinds only three fingers, and at an ostrich - and at all two, they form utolshchennuju, similar to a hoof and a callosity convenient for fast run. Each finger is supplied by a claw. The structure of the bird's paws rather variously also depends on a way of life of this or that kind.
Flight and plumage
In flight wings are set in motion by powerful flying muscles on which it is necessary from 15 to 20% of gross weight of a bird. These pair muscles are located on either side of kilja grudinnoj bones. Larger external muscles, being reduced, lower a wing, and much smaller internal muscles lift it, operating through block system of sheaves.
Instead of plain waves upwards-downwards wings describe the difficult trajectory similar to the eight in flight. Bordering a forearm mahovye feathers of the second order create a carrying power. Growing of fingers and a wrist mahovye feathers of the first order provide horizontal draught, being braided at movement covered downwards and cutting air, as if a propeller. Vertical draught is created also by the aerodynamic (bent) profile of a wing, supporting a bird in air for over a wing air moves faster, than under it at the expense of what the carrying power is created.
At slow flight this effect weakens, and the bird compensates loss, opening tiny "ёяшэръхЁ№" or wings, from the several feathers growing from rudimentary fingers on a bend of a wing which, like plane flaps, smooth air turbulences. There is also other way to keep height - widely to straighten feathers on tips of wings. The bird carries out all these difficult manipulations automatically, with speed and accuracy, inconceivable even for the advanced plane.
The Bird's feathers consist from keratina - the same as our hair and nails, - and under each old plumelet grows up new which about once a year pushes out it away. The feather represents the central core bordered from two parties with symmetric fans, consisting of set of small beards. Under a microscope it is visible that each small beard is supplied on all length nearby uncountable krjuchochkov. Krjuchochki the next small beards cling the friend to the friend. Cleaning plumelets, the bird touches their beak, clasps krjuchochki as if locks-lightnings, and the fan surface that it functioned in flight more effectively smoothes. The majority of birds in the tail basis has special kopchikovaja gland. By means of a beak they grease feathers with the fat allocated with gland. This procedure helps to keep structure of plumage and protects it from namokanija.
The Total of feathers depends on the sizes of a bird. Their humming-bird have more thousand, whereas at a swan - from above 25 000.
the Dazzling dress
Paints for modest camouflage plumage or the bright marriage dress undertake from two different sources. For example, pigments of type of melanin paint feathers in every possible shades black and brown, and karotinoidy - in red and orange. An iridescent sparkling of colours as at the humming-bird, it is created thanking special structure of the feathers reflecting only a part of a visible spectrum.
Except for some kinds, including penguins, the bird's feathers grow not randomly, and in strictly certain places and directions. During a seasonal moult the worn out or damaged feathers are dumped, and it on change the warm winter plumage or the bright marriage dress grows. The majority of birds dumps for once only a part of the mahovyh feathers not to lose ability to fly, but, for example, a duck, swans and geese dump all at once and month-other are adhered to the earth.
Extremely advanced systems of breath and blood circulation allow birds to maintain huge loadings in flight. At any mammal air in the course of breath arrives in lungs and through them leaves back. Instead of this enough uneconomical system "тфю§-т№фю§" providing replacement in lungs no more than 75% of air, at birds the through system of the breath operates, allowing to replace all air. At first it arrives in pair voluminous air bags behind lungs, then in lungs and already therefrom - outside through forward air bags.
This system allows blood to be enriched much more effectively by oxygen and to get rid of carbonic gas. To birds at all rarefied air of the big heights. The case of collision of a signature stamp with plane in heavens of the Western Africa at height of 11 274 m. the Person there instantly is known would be lost without an oxygen mask.
Heart of a bird, as well as heart of a mammal, consists of four chambers providing separate circulation arterial and a blue blood. Thanks to it rate of the bird's life much faster, than at fishes, amphibious or reptiles, in heart at which only three chambers.
Heart at a bird is much larger and stronger, than at an identical mammal on the size. Generally speaking, at small birds heart size in relation to weight of a body much more, than at larger kinds. The same concerns and frequency of palpitation.
a Food and digestion
In the course of evolution primary function of the forward finitenesses which have turned to wings, has been lost. Therefore to cope with food, to bring up baby birds, and to build dwelling to birds it is necessary paws and a beak.
The Bird's beak consists of the top and bottom jaws. These are bone vyrosty the skulls covered horn keratinovoj with a cover. However here it continuously grows, as constantly wears out from a mutual friction of jaws. Depending on a way of life and food structures, the bird's beaks have the most various form and size.
From a mouth the food arrives in a stomach on a narrow tube of a gullet. For many birds in a gullet is available voluminous vyrost, named a craw where for the further digestion the considerable stock of a forage can be stored in quiet conditions or for bringing up of baby birds.
Having offered for the sake of bolshej ease massive jaws and a teeth and having transferred the center of gravity to the body middle that it is better to operate it in flight, birds fray food in muscular department of a stomach. At the birds eating insects, fish or the meat, the concentrated gastric juice easily splits rather soft forage. But to such vegetarians as sparrows, titmouses or geese, it is necessary to swallow small stones which help to grind food in a stomach.
To the Same purpose - to simplification of a design – serves, and high concentration of urine which almost does not contain some water. Before deducing from an organism urine mixes up with firm excrement in a foul place (the bladder at birds is not present). At many carnivorous birds, including owls, seagulls, herons and halcyons, in a stomach firm lumps are formed of slices of bones, a wool and the other not digested rests of the eaten extraction which are belched from time to time.
Eggs, nests and baby birds
All birds conducting the sort from jajtsekladushchih of reptiles, too postpone eggs instead of vynashivanija posterities in an organism. To reduce to a minimum excess weight, they even postpone eggs on one, instead of all at once. Even genitals of birds - especially females - in the course of limiting simplification of a design became almost imperceptible, except for the pairing period.
In process of advancement on jajtsevodu, everyone impregnated jajtsekletka, hidden in nutritious zheltkovyj the sack, becomes covered albuminous (albuminovoj) by a cover and a firm limy shell which can be painted by some pigments, for example, victims eritrotsitami. Such protective drawing consisting of every possible specks and specks, preserves eggs against a sharp-sighted eye of predators. It is not excluded that on individual raskraske inhabitants of huge bird's markets distinguish the laying from the neighbour's.
The birds living in holes or hollows, egg usually white as they are easier for making out in the dark, and have no need to hide.
Nests protect from predators and cover from a bad weather a laying, baby birds and their parents. Some birds at all do not twist nests. We will tell, chistiki postpone eggs directly on narrow ledges of unapproachable rocks. Egg chistika is made narrower on one end, and if it casually to touch, will not roll down downwards, and, more likely, will describe a semicircle. Imperial and royal penguins constantly carry eggs on paws, having covered them from a frost with paunch folds. Other birds are content with pair the collected stones or branches, more relying on protective colouring of eggs. Many feathery spin intricate nests-baskets, and someone, aspiring to secure posterity, even constructs over them a roof. The most intricate nests skilfully twist some tkachiki and trupialy a New World, and also birds-tailors, is masterful sewing two leaves a web or other improvised material.
The Incubatory period, i.e. Time of transformation impregnated jajtsekletki in ready to hatch a baby bird, lasts from 12 days at small singing birdies till 79 days at some albatrosses. At the majority of small birds inkubatsija does not begin, all laying will not be postponed yet. But at many large kinds it begins immediately after adjournment of the first egg, and baby birds vyluplivajutsja serially. The posterity of many feathery, nesting on the earth, for example, marsh, is capable to run and find independently a forage almost right after births. But there is also other extreme measure - baby birds of many sparrow are born naked, blind and the first days require heat and care of parents.