External structure, skeleton, musculature
Birds are warm-blooded
animals, the forelimbs of which, due to adaptation to flight, turned into wings. The body is covered with feathers and is divided into head, neck, torso, tail, limbs. The head is small, bears a short beak, consisting of an upper and lower beak. The nostrils lie at the base of the beak. On the sides of the head are large eyes, equipped with movable eyelids and a nictitating membrane. Behind the eyes lie the ear holes, covered with an eardrum and covered with feathers. The head sits on a long movable neck. The body of the birds is ovoid, compact. The tail is short; tail feathers are attached to it. The forelimbs - wings - are located on the sides of the body. The hind limbs perform a supporting function when moving on the ground.
The skin of birds is thin, dry, devoid of skin glands. Only above the root of the tail is the coccygeal gland preserved. Its fatty secretion serves to lubricate feathers. It is especially strongly developed in waterfowl. The secret of the coccygeal gland in the sun turns into vitamin D, which is swallowed by the bird when cleaning the feather. The growths of the stratum corneum of the epithelium form the horny sheaths of the lower and upper jaws, scales on the tarsus and toes, and claws. The feather cover, consisting of contour and down feathers, also belongs to the horny formations of the skin.
An outline feather consists of a core, a point and a fan. The fan is formed by horny plates extending from the rod on both sides - first-order barbs, from which numerous second-order barbs with hooks located on them extend. The hooks of neighboring barbs, interlocking with each other, connect them into a light elastic blade of the fan. The lower part of the trunk, devoid of a fan, is called a point. Its base is immersed in leather and reinforced in a feather bag. The contour feathers are tiled overlapping each other, covering the entire body. Long and strong contour feathers that form the plane of the wing are called flight feathers, located on the tail - tail feathers.
Down feathers lie under the contour feathers. They have a very thin shaft, and the barbs do not carry hooks, therefore they do not form a fan. Down is down feathers with a very shortened shaft and heavily pubescent barbs that extend in a bunch from the ochin. Down feathers and down provide thermal insulation because contain a lot of air between the barbs.
The skeleton of birds is subdivided into axial skeleton, skull, skeleton of the chest, limbs and their belts.
The axial skeleton is divided into five sections: cervical, thoracic, lumbar, sacral, and caudal. The cervical vertebrae (from 11 to 25) are movably connected to each other and allow you to turn the head 180-270 degrees. The thoracic vertebrae (from 3 to 10), growing together motionlessly, form a complex sternum. The ribs are movably attached to the thoracic vertebrae. Each rib of birds consists of two parts - dorsal and abdominal, which are respectively articulated with the thoracic spine and with the sternum. Both parts of the ribs are also movably connected to each other. All birds (except ostriches) have a high keel on the sternum. The muscles that move the wing are attached to it.
All lumbar, sacral and part of the caudal vertebrae grow together and form a complex sacrum, with which the pelvic bones are motionlessly fused. The coccygeal vertebrae form the tail section. The last few caudal vertebrae fuse into the coccygeal bone. The steering feathers are attached to it.
The skull is bony, it is light and has a voluminous cerebral box. In front it ends with a beak, and on the sides it bears large eye sockets. The teeth and the secondary palate are absent.
The forelimbs are modified into wings and consist of the humerus, the bones of the forearm (ulna and radius). The bones of the wrist and metacarpus grow together to form an unpaired metacarpal-carpal bone. Of the fingers, only three are preserved, corresponding to the 2nd, 3rd and 4th fingers of the five-fingered hand. The reduction in the number of fingers and the formation of the metacarpal-carpal bone provides the strength of this wing section during flight.
The hind limb consists of the thigh, lower leg, tarsus and foot. The tibia and tibia are fused together. Due to the fusion of the bones of the metatarsus and tarsus, a tarsus was formed. Most birds have four toes: three forward and one backward.
The shoulder girdle is formed by three paired bones, the scapula, the coracoid and the clavicle. The clavicles grow together from below and form a fork.
The pelvic girdle gives solid support to the hind limbs due to the immobile fusion of the complex sacrum with the ilium. Due to the fact that the pelvic bones in the abdominal region are widely spaced and do not grow together, birds can lay large eggs. On the sides of the pelvis are the glenoid cavities for the heads of the femurs.
The muscular system, due to the variety and complexity of movements, is more differentiated than in reptiles. The most powerful muscles are located on the trunk and limb movements are carried out. The largest is the pectoral muscle, which serves to lower the wings. On the one hand, it attaches to the sternum, coracoid and keel, and on the other to the humerus. The subclavian muscle is located under the pectoralis and raises the wing. It starts from the coracoid and sternum and attaches to the head of the shoulder. About 30 muscles are involved in the movement of the hind limb. They are especially strongly developed in running birds. Neck muscles are well developed. Intercostal muscles are attached to the ribs.
Internal structure. Flight exchange features
Adaptation to flight, high physical activity determined the structural features of the digestive system of birds. The jaws form a beak - the organ for capturing food. No teeth. A conical tongue is located in the oral cavity. The secretion secreted by the salivary glands moistens food and facilitates its movement along the esophagus. In most birds, it has an expansion - a goiter, where food accumulates, swells, and undergoes chemical processing. During the hatching of the chicks, the wall of the goiter of some bird species secretes a nutritious secret - "milk", which the chicks are fed with. The stomach consists of two sections - glandular and muscular. In the thin-walled glandular region, rich in glands, food is exposed to enzymes. The gizzard has thick walls, is covered with a keratinized cover from the inside and serves for mechanical processing of food. The pebbles swallowed by birds also contribute to this. From the stomach, food enters the duodenum, where the ducts of the liver and pancreas open. Moving further along the small intestine, it is digested and absorbed. It is longer in herbivorous birds than in insectivores. The intensity of digestion is very high, which is ensured by thorough grinding of food and high activity of digestive enzymes. Sparrows, for example, digest caterpillars for 15-20 minutes, pigeons for grain - 2-3 hours. Undigested food debris enters the short colon, which opens into the cloaca. Rapid digestion of food and rapid bowel movement relieve the birds from excess weight, especially during flight.
Since birds consume a lot of energy, they feed often and a lot. The mass of food eaten per day in some small birds is 50-80% of their body weight, and in larger ones - 15-40%.
A high level of energy metabolism requires an intensification of the oxygen consumption process. In this regard, the respiratory system of birds is significantly different from the respiratory systems of other vertebrates. Through the nostrils, air enters the nasal cavity, pharynx, larynx, trachea, in the lower part of which is the vocal apparatus of birds. In the body cavity, the trachea is divided into two bronchi, which, entering the lungs, branch into 15-20 secondary bronchi. Some of them end blindly and are connected to each other by smaller bronchi, from which small bronchioles depart, densely braided with blood capillaries. This is where gas exchange takes place. Thus, the lungs of birds are not bags, as in amphibians or reptiles, but spongy, low-stretching bodies. However, their respiratory surface, despite their compactness, is comparable to that of mammals.
Part of the secondary bronchi, without interruption in the lungs, passes into the air sacs. These are thin-walled outgrowths of the mucous membrane of the secondary bronchi, located between various internal organs. Their processes penetrate the skin, between the muscles, in the bone cavity.
The act of breathing at rest is carried out by narrowing and expanding the chest. When you inhale, the sternum drops, when you exhale, it rises. During flight, the sternum is motionless and ventilation of the lungs is carried out with the help of air sacs. When the wings are raised, the bags stretch and the air partly enters the lungs, where gas exchange takes place, and partly into the air bags. Blood oxidation does not occur in them. When the wings are lowered, the air sacs are compressed and the air from them enters the lungs, where blood oxidation occurs again. Thus, in flight, gas exchange in birds occurs both during inhalation and exhalation. This mechanism is called double breathing. The adaptive value of such a mechanism is that an increase in the intensity of wing movements during flight is accompanied by an increase in gas exchange. In addition to participating in gas exchange, air sacs protect the body from overheating during large muscle work, removing excess heat with the exhaled air.
The circulatory system of birds is characterized by complete separation of arterial and venous blood currents due to the formation of a four-chambered heart, consisting of two atria and two ventricles. Like all terrestrial vertebrates, there are two circles of blood circulation. Venous blood from the right ventricle enters the lungs through the pulmonary arteries and is oxidized. Arterial blood through the pulmonary veins enters the left atrium. This is a small circle of blood circulation.
The systemic circulation begins in the left ventricle. Only one originates from it, the right aortic arch, which carries arterial blood to the organs. Venous blood is collected in the paired anterior and unpaired posterior hollow veins that flow into the right atrium. Here the systemic circulation ends. Birds have a high blood flow rate. It is provided by a high heart rate - from 200 to 600 per minute, a relatively large heart volume. This, along with the high oxygen capacity of the blood, as well as the intensive gas exchange in the lungs, makes it possible to effectively saturate the tissues of the body with oxygen, to maintain a high level of energy metabolism in them. Thanks to this, the birds
are able to maintain a constant body temperature, which significantly expands their adaptive capabilities, in conditions of seasonal temperature changes.
The excretory organs are paired secondary kidneys. They make up 1-2% of body weight. From each kidney, a ureter departs, opening into the cloaca. The bladder is missing. An economical consumption of water for excretion is achieved by the concentration of metabolic products due to the reverse absorption of water in the renal tubules, as well as in the cloaca.
The nervous system has a larger brain size than that of reptiles. The hemispheres are large, the lobes of the midbrain are well developed. In connection with flight, the cerebellum in birds is large; the surface of its middle lobe has transverse grooves. The olfactory lobes are small. 12 pairs of cranial nerves branch off from the brain. The spinal cord has thickenings in the shoulder and lumbar regions, from which nerves run to the limbs.
The senses play an important role in adapting to the environment. The eyes are relatively large, especially in nocturnal and crepuscular birds, and are the main organ for orientation in space. Color vision. The accommodation is double, because is carried out not only by moving the lens relative to the retina, but also by changing its curvature.
The organ of hearing consists of the inner and middle ear. The structure of the inner ear is distinguished by a greater development of the cochlea than in reptiles. In the middle ear, there is one auditory ossicle - the stapes. The eardrum is buried below the skin level. A short canal leads to it - the rudiment of the external auditory canal, covered from the outside with contour feathers. Most birds hear in the 30 Hz to 20 kHz range, but there are some that are capable of receiving ultrasounds. Voice and hearing play an important role in the sound communication of birds. The olfactory organs are poorly developed. The taste buds are located on the tongue, in the mouth. The organs of touch are represented by a variety of receptors located in the skin.
Adaptation to flight largely determined the mass, general contours of the bird's body and its constituent parts. The size and mass of the flying birds are limited by the small supporting force of the air. The mass of the largest of them (vultures, bustards, swans) is 14–16 kg with a wingspan of up to 3–4 meters (albatrosses, pelicans). The smallest birds include hummingbirds, with a body weight of 1.6–2 g. The body weight of birds that have lost the ability to fly is more significant: in penguins it reaches 40 kg, in ostriches - 100 kg.
Differences in external features (the shape of the beak, neck, front and hind limbs, etc.) are in accordance with the lifestyle of birds, with the degree of their mobility.
In general, birds are characterized by small head, long and movable neck, rounded compact body and short tailwhere the steering feathers are fanned out. Front limbsconverted into the wings, have different shapes, lengths and in a calm state the birds are pressed to the sides of the body.
Hind limbsvarying in length, shape, number of fingers and their orientation, depend on the habitat and the nature of the movements (walking, running, climbing on a vertical surface, swimming). Many species have four toes on their legs, however, there are birds with a deeper reduction of the toes: up to three (three-toed woodpecker) and two (African ostrich).
Due to the specialization of the limbs when performing movements (front - for flight, rear - for walking) bird body landing... Its front section is raised above the ground, body center of gravity moved to pelvic area belts. Skeletal changes and muscle restructuring can help maintain balance when walking on the ground (see the following topics).
The front of the head ends horny beakin which stand out upper beak and mandible (fig. 58). The horny covering of the beak is formed from the upper layer of the epidermis and is called ramfoteca... The length and shape of the beak is determined by the food specialization of the birds. At the base of the beak of a number of birds (parrots, birds of prey) there is wax- an area of \u200b\u200bbare skin, supplied with sensory cells.
External nostrils birds - narrow, slit-shaped, located in different areas of the beak or on the wax.
On the sides of the head are large eyeshaving movable eyelids and blinking membrane (third eyelid)... Behind the eyes are paired auditory holes, leading to the external auditory canals, ending in eardrum. At the base of the tail lies cloaca.
Leather birds, like reptiles, thin and dry,consists of epidermis and skin itself (cutis).Surface cells epidermal layerconstantly keratinizeand peel off.
Skin itselfconsists of dense, connective tissue coriumand subcutaneous tissue. In the coriumare capillaries of the circulatory system,grounds feathers (quills) and muscle fibers.
Subcutaneous tissue is a looser layer in which fatty formations are deposited.
Bird skin does not contain glands... The only exception is coccygeal gland, especially developed in waterfowl. The ducts of this gland, consisting of two lobes, open into special papillae of the skin, located in the region of the caudal vertebrae. Fat secret The gland is used to lubricate the feathers, as a result of which the feathers of birds become water-repellent. In addition, the fatty substance of the gland in the light is converted into vitamin D, which is essential for normal life. It is assumed that the coccygeal gland carries and information function when communicating with birds. The secretion is regulated by steroid hormones.
Birds living in arid climates (ostriches, bustards, parrots, some pigeon species) do not have a coccygeal gland. The feathers of some near-water birds (egrets) are also lubricated with a special substance, which is formed from the so-called "powders" - powder downgrowing on the back and chest.
The entire body of the bird is usually covered with feathers (in birds that feed on carrion, the head and neck are naked to varying degrees). Feathersare derivatives
skin and are horny formations with a specific morphology. The feather appears in the form of a tubercle of the connective tissue layer of the skin, which has an epidermal covering.
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| Figure: 60. Types of feathers: 1 - contour feather, 2 - down feather, 3 - down itself, 4 - filamentous feather, 5 - bristle. |
As it grows, the base of the tubercle goes deep into the skin, forms pen vagina and underlying papillasupplied with blood vessels. The shaft and fan barbs are formed from the outer part of the feather bud. The developing primordium is covered from above with a thin horny cap, which breaks at the end of feather formation, freeing two parts of the fan.
Feather cover is located on the body of a bird in a certain order and, depending on the structure, performs different functions. Allocate feathers of the chest, abdomen, sides of the body, uppertail, undertail, shoulder, etc.
For lightening the mass body in flight and providing the mechanism heat transferbird feathers are unevenly distributed, especially on the ventral side. Areas of the body with feathers are called pterilia, and those devoid of feather cover - pharmacies(fig. 59). The combination of such areas contributes to greater freedom of contraction of the muscles that determine body movement, especially in the limbs.
On the body of the bird are feathers of different shapes and buildings: contour, semi-fluff, fluff proper, filiform and bristle(fig. 60).
The basis of the feather cover is contourfeathers that are on the body ( covering), wings ( flywheel) and tail (steering). The contour pen has a special structure (Fig. 61), which is associated with a high functional load, especially during flight. Feather base ( ochin) is in the skin, and its outer part (kernel) carries thin elongated beards first order to which, thanks to hooks, fastened second beardorder (barbs). As a result of this adhesion, fan a feather having an inner and outer sides, and the feather is a double-sided elastic plate.
The bird can change the degree of wings and tail feathers opening, thus, the flight mode, which is especially important when changing its speed, direction, as well as hovering, taking off and landing.
Greater maneuverability of flight is determined by the special arrangement of the contour feathers on the forelimbs (Fig. 62): to brushesfastened paramountflight feathers, k forearm - secondary flight, to shoulder - tertiary flywheels... On the phalanx of the first finger there is winglet, consisting of several feathers and performing a special role during bird take-off (delays the passage of air forward). It is especially well developed in poorly flying birds. The bases of the flight and tail feathers are covered coveringfeathers.
The rest of the feathers are mostly located on the body between the coverts. They perform functions heat regulation and touch.
Semi-duvet the feather is partly arranged like a contour (its upper part); the lower part is represented by fluff, which has second-order beards no hooks, as a result of which a fan is not formed in this part.
Fluff itself has a structure similar to the lower part of a semi-down feather; only the shaft is very short, so that the long first-order barbs extend practically from one point. Downy cover is mainly provided by chicks. A number of adult birds also have a significant amount of down. Waterfowl and those living in places with a harsh climate ( eiderPolar region).
Thread featherconsists of a long, thin rod, at the end of which there are reduced barbs.
Seta is a thin bar without barbs. The bristles are most often located in the corners of the mouth, increasing the angle of food capture. Bristles are well developed in insectivorous birds that capture food in flight (swifts, swallows, nightjars). In addition, like other feathers, the bristles perform feeling function.
Colorationplumage of birds, determined mainly by the presence or absence pigments. Dark coloration is determined melanins, bright - lipochromes (carotenoids, pterins)... The combination of these pigments gives different colors and shades. The white color of the feather is due to the colorless horny substance filled with air. In many birds, body color is created and interferencelight falling on the uneven surface of feathers (pigeons, hummingbirds).
All birds are characterized by a regular change of plumage, or molt. During the year, there are two or three molts, depending on the speed of erasure of the feather cover in different birds. The frequency and extent of molting is also related to seasonal changes and bird reproduction. Fast and constantly flying birds molt gradually and longer in time (birds of prey, swifts, swallows).
Figure: 62. Scheme of the wing skeleton and the location of the flight feathers:
1 - primary flight feathers, 2 - secondary flight feathers, 3 - tertiary flight feathers, 4 - winglet, 5 - ligament that strengthens the bases of flight feathers, 6 - leathery flying membrane, 7 - humerus, 8 - radius, 9 - ulna, 10 - brush, 11 - phalanx of the first finger
A complete and quick change of plumage is typical for birds living in forest, shrub and grassy habitats. During such a molt, many species (chickens, anseriformes, guillemots, loons, grebes, shepherds) prefer to be in secluded places, fleeing from enemies.
The change of feather cover is characterized by seasonal differences in its composition. It is noticed that winter plumage birds consist of a greater number of feathers, among which the content of down feathers increases. The length of feathers and their density on the body increase.
goal: To reveal the features of the external structure of birds in connection with the flight.
Equipment: A stuffed bird, a set of feathers (contour, down, down), tweezers, a magnifying glass.
The task:
1. Consider a stuffed bird. Find the main divisions of the body. Name them.
2. Consider the bird's head. Pay attention to its shape, size. Find a beak, examine its structure. Find eyes, pay attention to their location. Find the ear cavity.
3. Consider the body of the bird. Determine its shape. Determine the location of the wings and legs.
4. Pay attention to the external structure of the limbs. What are the tarsus and toes covered with? Recall which animals have such a cover.
5. Consider the tail of the bird. Write down the names of the feathers located on the tail and wing, count their number.
6. Explore the set of feathers. Find an outline pen, study its structure, name the main parts. Use a magnifying glass to examine the fan. Sketch the structure of a contour pen, sign the names of its main parts.
7. Consider a down feather. Find the point and fan. Sketch this feather and sign the names of its main parts.
8. On the basis of the external structure, note the adaptation of birds to flight.
Working process:
1. The main parts of the body: head, body.
2. Relatively small head with a beak formed by bony jaws. On both sides it is covered with horny sheaths. The beak has nostrils. On the sides of the head there are large eyes; closer to the back of the head, under the feathers, the ear pits are hidden, at the bottom of which are the eardrums.
3. The whole body of the bird is adapted for flight. The forelegs are turned into wings, the body is streamlined.
4. Tarsus and toes of the bird are covered with skin scales like those of lizards.
5. Tail feathers are located on the tail of the bird. With their help, birds can control the direction of their movement.
6. Contour feathers are located on the wings. The main structure of the feather is a fan and a core with a quill. The fan consists of I and II order barbs.
Conclusion: The bird's body is streamlined, which reduces drag during flight. The flight itself is carried out by wings with contour feathers and a tail with helmsmen.
Laboratory work No. 9 "The structure of the skeleton of a bird" 26.02
Goal. To study the features of the structure of the skeleton of birds. Mark the features associated with the flight.
Equipment: bird skeleton, tweezers.
Working process
1. Consider the skeleton of a bird. Determine the shape of the skull. Consider the bony base of the beak and large eye sockets, the jaw-to-skull junction, and the skull-to-spine junction.
2. Consider the sections of the spine. Name them.
3. In the cervical spine, pay attention to the structure of the first two vertebrae, to the saddle shape and the movable connection of other vertebrae. Note the significance of this feature in the life of the bird.
4. Find the thoracic spine, pay attention to the motionless connection of the vertebrae. Consider the structure of the sternum and ribs.
5. Name the bones of the girdle and free forelimbs. Pay attention to the bones of the shoulder, forearm, buckle, fingers.
6. Find the belt of the hind limbs. Consider it, paying attention to the strength of the connection of the pelvic bones with the spine. Explain the significance of this feature of the skeleton in the life of a bird.
7. Consider the bones of the hind limbs. Name them. Pay attention to the tarsus - the long bone of the foot. Count the number of fingers.
8. To mark in the structure of the skeleton of the bird the features of fitness associated with flight.
Working process:
1. Skull small enough with large eye sockets;
2. Spine: cervical (9-25 vertebrae), thoracic (3-10), lumbar (6 vertebrae), sacral (2 vertebrae), caudal.
3. The first 2 vertebrae - atlas and epistrophy provide mobility of the bird's head.
4. The thoracic vertebrae are fused into a single dorsal bone. The ribs are attached to the thoracic vertebrae. The thoracic vertebrae, ribs, sternum form the rib cage that protects the internal organs.
5. Wing skeleton: shoulder, forearm, hand. Some of the bones of the wrist and metacarpus have grown together into a buckle. The skeleton of the free hind limb consists of the femur, the bones of the lower leg, fused together, and the foot. Part of the bones of the tarsus and all the metatarsal bones are fused into the tarsus.
6. The lumbar, sacral and part of the caudal vertebrae form a complex sacrum. It creates support for the hind legs. The pelvis in birds is open - the pubic bones do not grow together, but widely diverge to the sides. This allows the birds to lay their eggs.
7. Bones of the hind limb: thigh, lower leg, tarsus, phalanges of the fingers. Birds have 4 toes (rarely 3).
Conclusion: The musculoskeletal system reflects well the fitness of birds to fly. The skeleton is lightweight and durable. Lightness is provided by the pneumaticity of bones, strength - by their fusion. In the hand, the bones have grown together into a buckle, in the foot - into a tarsus. The largest and most powerful flying muscles begin at the keel of the sternum and attach to the wing bones by tendons.
The study of the external structure of birds allowed scientists to establish the characteristic features thanks to which they adapted to flight. It is their presence that makes these animals absolutely unique representatives.
Features of the structure of birds
The ancestors of birds are reptiles. And this is not just a guess. The unfeathered part of the bird's leg, which is called the tarsus, is devoid of feather cover and is covered with scales. They have a similar structure with the same structures in lizards and snakes. In the process, progressive features of the structure were acquired. This is the appearance of a four-chambered heart in which the septum is located. Thanks to her, the venous and arterial blood is completely separated. This change led to the emergence of warm-bloodedness. It is the ability to maintain a constant body temperature that is independent of environmental conditions. Thanks to this, birds can stay at high altitudes for a long time in low temperatures.
The external structure of birds also determines their ability to fly.
Body parts
The body of birds consists of the head, neck, trunk and limbs. They all have their own characteristics, often associated with the conditions of existence. The eyes are located on the head. Their size varies depending on how large the body is. In predators, eyes are the same in volume as humans. And in chickens, they are equal in weight to their brain. All birds are color-discriminating. And their visual acuity is simply amazing. For example, a peregrine falcon predator clearly sees prey at a distance of about 1 km.
She is very mobile. Owls, looking out for prey, are able to turn it 270 degrees.
The features of the external structure of birds are determined not only by the ability to fly, but also by the nature of the food. First of all, this concerns the structure of the beak. It is the initial section of the digestive system that leads to the oral cavity.
Beak
The beak is the calling card of every bird. It is formed by a hard horny substance. Its component parts are the supra- and mandible. The beak will replace many organs for birds, performing the functions of the mouth apparatus, nose and forelimbs.
The variety of beak shapes is due to the nature of the food. Herons, which prey on aquatic creatures, have a long and pointed shape. With its help, these birds can easily catch a frog or pierce a fish through and through. With a crossed beak, it is easy to gnaw the cones and get seeds out of them.
Predators attack their prey. At the same time, with the help of a sharp bent beak, they easily tear it into pieces.
The woodpecker gets food in a different way: its beak is like a chisel. With them, the bird makes holes in the wood, from which it extracts the larvae of insects.
Limb features
The external structure of birds is also due to the structure of the limbs. The upper ones are turned into wings. Their skeleton consists of the shoulder, forearm, and hand. Covering feathers are attached to the covers of the wings. This structure makes birds capable of flying. The wings set in motion specialized muscles that are attached to the flat bone - the keel.
With the help of the lower limbs, the bird lands and pushes off the ground, moves along the surface. And flexible toes allow you to firmly hold on to any surface. They end with sharp claws, which are especially well developed in predators. With them, falcons, golden eagles and peregrine falcons dig into the victim, not giving it the slightest chance.
Veils
The skin of these animals is dry and devoid of glands, like reptiles. However, it does have a coccygeal gland. With secretions of her fat-like secretion, they lubricate the feathers. As a result, they do not absorb moisture.
The unique external structure of birds is due to the presence of a feather cover. It is derived from the skin.
Depending on the structural features and functions performed, several types of feathers are distinguished. Contour lines are divided into flywheels, coverts and steering. The former are located on the wings and provide the ability to fly. The coverts are similar in location and function. And the helmsmen are concentrated on the tail, they act as a rudder during flight, helping the birds to carry out rather complex maneuvers. The contour feather is based on a horny core surrounded by a fan. It, in turn, consists of barbs of several orders, tightly connected by hooks. The part of the rod that is devoid of a fan and immersed in the skin is called a quill.
The next type of feather is downy. They are located under the outline. Their functions are to maintain heat and insulate the body. A similar function is performed by down, in which the beards leave in a bundle in the form of a brush.
Some bird species have specialized filamentous feathers. Located in the corners of the mouth, they function as organs of touch.
External structure of birds and habitat
The features of the morphological structure of birds largely determine the conditions of their habitation.
A bright representative of ratites is not capable of flight. Therefore, he has high powerful legs, on which there are only two toes. All this contributes to a fast run and makes it the largest bird on the planet. And thanks to them, they can look out for small land animals that feed on.
Penguins, despite having a keel, are also unable to fly. A large fat layer, which is necessary for life in the harsh northern conditions, does not allow them to soar into the air. This is offset by their ability to swim perfectly. This is possible due to the fact that the front limbs are modified into elastic fins. So penguins fly in the water.
The life of representatives of the order Anseriformes is closely connected with water. That is why they have an elongated body, shortened and pushed back legs. This allows the birds to dive more easily under the water for food. Swimming membranes are located between the toes. An interesting structure has a beak. It is wide and flat in shape, and inside its upper part there is a system of horny plates. With their help, swans, mallards and eiders filter out food.
Owls and eagle owls have a hooked beak, powerful and curved claws on their toes, long wings, and a short tail. Such structural features allow them to be forest predators. The thick and soft plumage ensures a quiet flight.
Features of the external structure of birds: table
Birds are a group of warm-blooded animals adapted to flight. The table lists the main features of their morphology.
Thus, the following conclusion can be drawn. The study of the external structure of birds indicates that its main features make these animals capable of flight.
Features of the external structure and integuments of birds.
OK. No. 23. Biology. 7th grade
Ornithology- the science of birds. All features of birds are associated with the development of airspace and adaptation to flight.
The body of the birds is covered feathers - perform a heat-insulating function, provide streamlining of the body, form load-bearing planes in flight (wings, tail). Feathers are derived from leather.The skin of birds is dry and devoid of glands. The only gland - coccygeal(gives off fat, which birds lubricate feathers to make them elastic and non-wetting).
Pen consists of chin, rod (axial part of the pen) and fan. Ochin the feather is immersed in the skin, and the fans extend from the shaft. Kernel - a dense horny tube. Fan formed by barbs of the first order, from them are barbs of the second order with small hooks. The barbs are hooked to each other.
Contour feathers - cover the body of birds and define its contours; provide flight capability and protect the bird. Flight feathers - make up the flying plane of the wing. Coverts - smaller feathers covering the body of birds. Helmsmen - large and resilient feathers forming a tail fan; direct the flight. Downy - a thin rod that looks like brushes; do not form a fan, warm the bird. Fluff - a shortened rod, barbs extend from it in a bundle. The function of down feathers (down) is to keep a layer of air near the skin and keep warm.
Sense organs: smell - poorly developed, with the exception of some species (predators, ducks, woodpeckers). Most important in birds is vision... The eyes are large in size, equipped with an upper and lower eyelid, as well as a blinking membrane. Exceptional visual acuity, the field of vision is much larger than that of other animals - the eyes are located on the sides of the head. Organ of hearing consists of the inner, middle and outer ear. External auricles are absent, but in many birds their function is performed by ear feathers (well developed in owls). Flavoringreceptors are located in the walls of the mouth; there are receptors in the skin touch and pain, thermoreceptors.
Skeleton -durable and lightweight. Bones have air pockets. Strength gives the skeleton fusion many bones. A single bone is skull, in which only the lower jaw is movably connected.
Bird skeleton:
1 - lower jaw; 2 - upper jaw; 3 - skull; 4 - cervical spine; 5 - clavicle;
6 - coracoid (crow's bone);
7 - scapula; 8 - shoulder;
9 - forearm; 10 - buckle;
11 - phalanges of the fingers;
12 - ribs; 13 - sternum;
14 - keel of the sternum; 15 - complex sacrum; 16 - tail spine; 17 - coccygeal bone; 18 - thigh; 19 - shin; 20 - tarsus; 21 - phalanges of fingers
The spine consists of fivedepartments: cervical, thoracic, lumbar, sacral and caudal. The thoracic vertebrae grow together into a single back bone... Ribs are attached to them, which are connected to the sternum. The thoracic vertebrae, ribs and sternum form chest (protects internal organs).
The flying birds sternum It has keel, to which the pectoral muscles are attached, which move the wings. They grow together with the spine pelvicbones. The lumbar, sacral and part of the caudal vertebrae form complex sacrum, which creates a secure support for the hind limbs. The pelvic bones do not grow together, but widely diverge to the sides. This allows the birds to lay large, hard-shell eggs.
Forelimb belt 2 shoulder blades, 2 fused into a fork clavicle (they absorb sudden shocks when lowering the wings) and 2 large crow bones... Front free limb: shoulder, forearm and hand... Some of the bones of the wrist and metacarpus grow together into a single section - buckle. Free hind limb skeleton consists of thighs, shin bones fused together, and feet. Part of the tarsal bones and all the metatarsal bones fused together and formed a single bone - tarsus... The legs of most birds are four-toed.
