The structure of the skeleton of a bird. Class Birds Features of the structure of the skeleton of birds associated with
The skeleton of birds consists of several sections: the skull, spine, limb belts and limbs. It is light due to the presence of air cavities in the bones. In flightless and diving birds, it is heavy. Compared with reptiles, birds increase the strength of the skeleton due to the fusion of bones.
Pattern: Rock Pigeon Skeleton
V bird skull they distinguish a rounded cranium containing the brain, very large eye sockets, toothless upper and lower jaws - the bone base of the beak. In it, all the bones, except for the lower jaw, grow together, since when pecking, the skull experiences a large load.
cervical spine long, and the vertebrae in it are of a special, saddle shape. Therefore, it is flexible, and the bird can freely turn its head back 180 ° or peck food around it without crouching or turning its body.
Thoracic vertebrae almost motionless, the lumbar and sacral are firmly fused together and serve as a reliable support for the body. This is especially important during flight.
The last few tail vertebrae in a bird fuse into one coccygeal bone, which serves as the basis for attaching the tail feathers.
The chest in birds is formed by the spine, ribs and wide sternum - sternum, similar to a boat: the sternum has a high ridge from below - keel, muscles are attached to it, lowering and raising the wings.
Attached to the thoracic vertebrae ribs. The rib of a bird consists of two parts. The upper part of it is movably fastened to the spine, the lower part - to the sternum.
Forelimb belt It is composed of three paired bones in birds: crows, shoulder blades and clavicles. The clavicles fuse at their lower ends and form a fork. The bird's wing skeleton consists of one humerus, two bones of the forearm - the ulna and the radius - and several bones of the hand.
Unlike the five-fingered forelimb characteristic of most amphibians and reptiles, the forelimb of a bird - the wing - has only three fingers. Several small bones of the hand fuse with each other and form one complex bone. By reducing the number of fingers, as well as by merging the small bones of the hand, the strength of this section of the wing, which bears the greatest load during flight, is achieved. The fork in the forelimb belt increases strength and at the same time softens the jolts during the flapping of the wings.
Rear limb belt consists of three pairs of pelvic bones, which grow together with the lumbar and sacral spine and the first tail vertebrae. On the sides of the pelvic bones there are articular fossae, to which the hind limbs are movably attached.
In the leg, a rather thick femur is distinguished, a thinner and longer tibia, consisting of two fused bones, tarsus and fingers. Tarsus is characteristic only for birds. In it, several small bones of the foot have fused into one bone. The bones of the fingers are attached to the lower end of the tarsus. The tarsus helps to lift the body above the surface and softens the shock when landing after a flight.
Musculature of a bird
The largest muscles in the body of all flying birds are paired large pectoral muscles. Their mass is the same as that of the rest of the muscles. These muscles originate from sternum and her keel, and end with shoulder. The lateral surfaces of the keel serve as the site of attachment of these most powerful muscles of the bird. The main work of the pectoral muscles is the lowering of the wings. Raise the wings of others, less strong subclavian muscles located under the pectoralis major. Leg muscles are also well developed. Thrown through the joints of the legs tendons, the ends of which pass into the fingers. When a bird sits on a branch and squats, these tendons are stretched, the fingers are bent and tightly embrace the branch. Therefore, birds can not only sit, but also sleep peacefully without falling off the branch. Intercostal muscles are attached to the ribs and their processes, which provide a change in the volume of the bird's chest during breathing.
The muscles of the neck in birds are involved in the movement of the head - in turning, raising and lowering it.
The skeleton of birds is adapted for flight. This is expressed in the fact that the bones are light, and the skeleton itself is strong, the forelimbs of birds are modified into wings, and the hind limbs are adapted to move along the surface.
The lightness of the skeleton of birds is achieved by the fact that the bones themselves are thin, in a number of bones there are cavities filled with air, and there are many tubular bones.
The strength of the skeleton arises from the fusion of many bones together.
In the skeleton of birds, the following parts can be distinguished:
- skull with beak
- spine
- ribs with sternum and keel
- forelimb belt
- forelimbs
- hind limb belt
- hind limbs
Bird skull bones grow together. This makes it durable, which is important when the bird wields its beak, the upper part of which is fixedly fused to the skull. The skull articulates with the first cervical vertebrae with one condyle. Birds have large eye sockets. The beak consists of the mandible and mandible covered with horny substance. There are no teeth.
V spine in many places the vertebrae fuse together. But this does not apply to the cervical region. The neck of birds is very flexible, so they can turn it 180 degrees. The number of cervical vertebrae depends on the type of bird.
The thoracic vertebrae grow together. The lumbar, sacral, and first vertebrae of the caudal region also fuse together, forming a complex sacrum, which provides powerful support for the hind limbs. Next come the movable tail vertebrae. The last vertebrae fuse again to form the coccygeal bone. Steering feathers are attached to it.
Ribs birds have a special structure. Each rib consists of two parts (upper and lower), usually movably connected to each other. The upper parts of the ribs are movably connected to the spine. The lower parts of the ribs are connected to a fairly wide sternum.
The thoracic vertebrae, sternum, and ribs form the ribcage, which protects the internal organs. Each rib has an uncinate process that overlaps the posterior rib. This gives additional strength to the chest of birds.
A feature of the skeleton of birds is the presence on the sternum keel(with rare exceptions). Powerful muscles are attached to it, which are responsible for raising and lowering the wings in flight. Flightless birds (but not penguins) usually do not have a keel.
Shoulder girdle of birds consists of pairs of clavicles, shoulder blades and coracoids (crow bones). The clavicles fuse together at their lower ends and form a fork. The fork expands the base of the wings and plays the role of a shock absorber in flight. The shoulder blades of birds are narrow and long.
Bird forelimb skeleton(wings) consists of the humerus, radius and ulna (together form the forearm), hand (free bones of the wrist, buckle and finger rudiments). The buckle is formed by the fusion of the bones of the metacarpus and part of the bones of the wrist. No birds have forelimbs used for movement on the ground. The number of finger rudiments is usually three.
V hind limb girdle in birds, the pubic bones do not fuse together, and the ischial bones do not fuse together. This makes the pelvis of the birds what is called open. Due to the presence of an open pelvis, birds can lay large (in relation to their body size) eggs. The pelvis of birds (namely, the ilium) is fixedly fused with a complex sacrum. The pelvic bones are fused together (the pubic, ischial and ilium bones are fused together on each side).
Skeleton of the hind limbs of birds consists of the femur, tibia and tibia (together form the lower leg), tarsus, and finger bones. The tarsus is formed by the bones of the tarsus and metatarsus, which grow together. The fibula in the skeleton of birds is reduced and adheres to the tibia.
Class Birds Features of the structure of the skeleton of birds associated with
Most birds have four fingers, three of which point forward and one backward. However, there are also three-toed and even two-toed birds. The toes have well developed claws.
Skeleton bones
Axial skeleton
Scull
brain department
Facial department
The facial section is less developed. The composition of the facial skull includes paired bones: incisor, nasal, maxillary, palatine, pterygoid, zygomatic, square, square-zygomatic, mandibular and hyoid. The vomer belongs to unpaired bones.
The internal structure of birds (skeleton and muscles)
Birds have no teeth. The nasal, incisive and maxillary bones, fused together, form the upper beak - the bone base of the upper part of the beak. The mandible at the junction with the frontal part is elastic, which determines its relative mobility. The oral end of the lower jaw serves as the bone base of the mandible. The square bone contributes to significant mobility of the lower and upper parts, which is important when swallowing large pieces of food.
Torso skeleton
cervical
Thoracic
The sternum is very well developed, as it serves as an attachment site for powerful pectoral muscles that determine flight. On the ventral surface of the sternum there is a crest - a long keel. Its length is due to the peculiarity of the development of the pectoral muscles and internal organs.
tail section
Skeleton of the thoracic limbs
Shoulder girdle
Free limb skeleton
Skeleton of the pelvic limbs
Pelvic girdle
Free limb skeleton
On this page, material on the topics:
Why do birds have a light skull
Drawing of the peripheral skeleton of a bird
Departments of the skeleton in birds and their bones
Divisions of bird skeletons
Name the divisions of the bird community
Skeleton bones
The bones are pneumatic, filled with air from the air sacs. In female birds, secondary spongy bone tissue is formed inside the tubular bones.
Axial skeleton
Scull
The skull of birds is very light, clearly divided into brain and facial sections.
brain department
The brain section consists of the occipital, sphenoid, temporal, parietal, frontal, lacrimal and ethmoid bones fused together.
Facial department
The facial section is less developed. The composition of the facial skull includes paired bones: incisor, nasal, maxillary, palatine, pterygoid, zygomatic, square, square-zygomatic, mandibular and hyoid. The vomer belongs to unpaired bones. Birds have no teeth. The nasal, incisive and maxillary bones, fused together, form the upper beak - the bone base of the upper part of the beak. The mandible at the junction with the frontal part is elastic, which determines its relative mobility. The oral end of the lower jaw serves as the bone base of the mandible. The square bone contributes to significant mobility of the lower and upper parts, which is important when swallowing large pieces of food.
Torso skeleton
cervical
The cervical spine is of great length. In chickens, it consists of elongated vertebrae. The 1st cervical vertebra is connected to one spherical condyle of the occipital bone. This feature of the occipital-atlant joint gives great mobility to the head of birds.
Thoracic
The thoracic spine in birds of different species has a different number of vertebrae. The middle vertebrae fuse into a single bone.
The number of pairs of ribs corresponds to the number of thoracic vertebrae. The rib consists of vertebral and sternal parts. The ribs, the ends of which are connected to the sternum, are called sternal. The first 2-3 ribs do not connect with it and are called asternal. At the caudal edge of each rib there is an uncinate process that joins with the next rib. Thanks to these processes, the chest of birds acquires greater strength.
The sternum is very well developed, as it serves as an attachment site for powerful pectoral muscles that determine flight.
Bird class
On the ventral surface of the sternum there is a crest - a long keel. Its length is due to the peculiarity of the development of the pectoral muscles and internal organs.
Lumbar and sacral
The lumbar and sacral vertebrae fuse with each other, as well as with the pelvic bones, forming a solid foundation for the limbs.
tail section
The tail section of the spinal column is inactive. The last tail vertebra is elongated, called the coccyx, or pygostyle.
Peripheral skeleton (limbs)
Skeleton of the thoracic limbs
The skeleton of the thoracic limbs of birds differs sharply from the thoracic limbs of mammals. In birds, they have changed and turned into wings.
Shoulder girdle
The shoulder girdle is made up of three bones: the scapula, the coracoid, and the clavicle. The shoulder blade looks like a thin narrow plate. Its lower end, together with the coracoid bone, forms the articular fossa for the humerus. The coracoid bone is tubular, with its upper end connected to the scapula and clavicle, and its lower end to the sternum. The clavicle at the top connects to the scapula, and at the bottom it fuses with the bone of the same name on the other side.
Free limb skeleton
The skeleton of the free limb is divided into three parts: the humerus, forearm and hand. The humerus is hollow, through a special hole it is filled with air from the interclavicular sac. The forearm consists of the radius and ulna. Between them is the interosseous space. The brush of birds is significantly changed. It has three metacarpals, fused together, and three fingers, greatly reduced. Of these, only the third finger has two phalanges, the remaining fingers have one phalanx each.
Skeleton of the pelvic limbs
The skeleton of the pelvic limbs is divided into the pelvic girdle and the free limb. Material from the site http://wikiwhat.ru
Pelvic girdle
The pelvic girdle consists of the iliac, ischial and pubic bones, which fuse with the lumbar and sacral vertebrae. Unlike mammals, in birds, the pubic and ischial bones of one side do not fuse with the bones of the same name on the other side. Therefore, the lower part of the pelvis is open and does not interfere with the passage of a large egg during oviposition.
Free limb skeleton
The skeleton of the free limb is subdivided into the femur, lower leg and foot bones. The tarsal joint of a special structure. It has no short bones; they fuse with the tibia and metatarsal bones. The metatarsus is made up of three fused bones. Of the four fingers, the first finger is poorly developed and directed backwards; II, III and IV fingers are directed forward. I finger consists of two phalanges, II - of three, III - of four, IV - of five.
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What is the external and internal structure of birds? How are they different from other classes of animals? What signs are characteristic only of birds? You will find answers to these questions in this article.
General characteristics of birds
Birds are a class of animals whose body is covered with feathers. They have a constant and high body temperature and are active at any time of the year. The ability to fly is characteristic of most representatives of this class. The external and internal structure of birds is subject to this feature.
Birds can easily change their place of residence depending on the conditions. Due to the ability to fly, the class is widespread, found in a wide variety of conditions throughout the planet. There are about 9000 species of birds.
Birds also have a pronounced concern for their own offspring. Reproduction occurs with the help of large, calcareous eggs.
The external structure of birds
The body of a bird consists of a head, a movable neck, a teardrop-shaped body and limbs. The skin is thin and dry due to the absence of skin glands. Most birds have a gland that serves to lubricate feathers - coccygeal. It is especially well developed in waterfowl. The secret secreted by the gland serves to maintain the elasticity of the feathers and prevents them from getting wet. In some parrots, pigeons, bustards), the function of lubrication is carried out by special powdery feathers, which form a powder when broken off.
Birds may have various growths on the beak, legs, head. In some species of birds (for example, birds of prey and parrots), the base of the beak is covered with soft wax. On the legs there may be plates, fringes, membranes.
The external and internal structure of birds directly depends on the lifestyle. The shape of the body, head, paws and tail, wings can be very diverse. All this depends on the habitat and the method of obtaining food.
The external structure of birds. Plumage
Only the class of birds has a feather cover, therefore they are also called feathered. The plumage fits snugly to the body and gives it a streamlined shape. The cover is light and retains heat well, which helps to incubate the eggs. Some feathers, due to their structure, provide the possibility of flight (steering and flywheels).
The feathers themselves are similar to the scales of reptiles. The structure of the feather is as follows: its trunk consists of a dense rod, ending with a chin (hollow end). Fans are attached to the rod. They consist of horny plates - beards. Barbs extend from the rod, having branches called barbs. Some of them are strewn with hooks, with which they are connected to neighboring beards without hooks. A large feather may consist of a million beards.
This structure provides the density of the fan. During flight, very little air can pass through the feather. If the barbs are separated, the bird will straighten them with its beak when cleaning feathers.
By functionality, feathers can be divided into two groups: down and contour. Downy feathers have a loose fan. There is also just fluff - feathers, consisting of almost only beards, with an undeveloped core. There are also bristle feathers, which, on the contrary, consist of rods, with little or no barbs. There are also hair-like feathers on which the function of touch is assigned. Contour feathers can be divided into primary, tail, covering and integumentary. Each type of pen performs its own function. The varied color of feathers is due to the presence of pigments.
Musculoskeletal system
The features of the internal structure of birds are associated with a trait inherent only in birds - the ability to fly. light, but at the same time has great strength, consists of thin hollow bones. It includes the skull, spine, limb girdles, and limb bones. The skeleton protects the internal organs.
The internal structure of birds suggests a large volume of the skull. Eye sockets are enlarged, jaws form a beak, teeth are missing. The spine is divided into 5 sections: cervical, thoracic, lumbar, sacral, caudal. The vertebrae of the cervical region have a special structure, thanks to which the bird can turn its head 180 degrees.
The thoracic vertebrae fuse and form a single bone to which the ribs are attached. In flying species of birds, there is a large outgrowth on the sternum, on which powerful wing muscles are attached. The vertebrae of the lumbar and sacral regions also fuse to serve as a reliable support for the pelvis, and the caudal vertebrae fuse into a single coccygeal bone to become a support for the tail feathers.
The shoulder girdle is made up of three pairs of bones: the clavicle, scapula, and crow bones. The wing consists of the humerus, forearm and bones of the hand. The bones of the pelvis fuse with the vertebrae and serve as a support for the lower extremities. The leg consists of the thigh, lower leg, tarsus (several fused bones of the foot) and toes.
The muscles of the bird, located from the keel to the shoulder, ensure the work of the wings. In flying birds, the muscles in this part are especially well developed. The muscles of the neck provide the movement of the head. The internal structure of birds is interesting in the area of \u200b\u200bthe structure of the muscles and tendons of the lower extremities. Through the joints of the legs, tendons stretch, which end in the fingers. When a bird perches on a tree and bends its legs, the tendons tighten and the toes wrap around the branch. Thanks to this feature, birds can sleep on branches, their fingers do not open.
Digestive system
We continue to study the internal structure of birds. general characteristics begins with the first section of the digestive system - the beak. It is the bones of the jaws, covered with horny sheaths. The shape of the beak depends on the method of obtaining food. Feathers have no teeth. Food is swallowed whole, from a large piece with the help it can tear off suitable pieces.
The esophagus of birds is able to stretch significantly. Some types of birds can fill it with food and not experience discomfort. At the end of the esophagus, there may be a goiter - a special extension adapted to store food.
The stomach of a bird consists of a glandular and muscular section. In the first, the secretion of gastric juice occurs, which softens the food, and in the second, it is grinded. This process is facilitated by pebbles that are swallowed by birds. The stomach is followed by the intestine, ending in a cloaca. The ureters and excretory tracts of the reproductive organs also open in the cloaca.
Respiratory system
We continue to study the internal organs of birds. The internal structure of birds is subject to the need to ensure flight. This concerns and which is represented not only by lungs, but also by air sacs located in the free space between internal organs. These sacs are connected to the lungs and have the important function of providing breathing during flight. At rest, the bird breathes with the lungs, working with the chest.
In flight, thanks to the work of the wings, the air sacs expand and contract, supplying air to the lungs. The faster the bird flaps its wings, the more often the air sacs contract. For example, a dove takes 26 breaths at rest, and up to 400 in flight. Thanks to active air circulation, the bird's body cools down. Oxygen-enriched air from the breathing bags enters the lungs, which does not allow the bird to suffocate.
The circulatory system of birds
Features of the internal structure of birds can also be found by studying the circulatory system, which is represented by two circles of blood circulation and a four-chambered heart. The large and small circles of blood circulation are completely separated, that is, arterial and venous blood do not mix. The heart consists of two atria and two ventricles.
The heart muscle is capable of accelerating its work dozens of times, for example, at rest, the heart of a pigeon contracts 165 times per minute, and during flight - 550 times. The structural features of the circulatory system of birds are caused by a high level of metabolism. The heart has a large volume, the pulse is frequent, the blood is saturated with oxygen and sugars - all this provides both an intensive supply of all organs with the necessary substances, and the rapid removal of metabolic products.
sense organs
The organs of smell in birds are poorly developed. Most birds are unable to distinguish smells. The internal structure of birds, especially the organs of hearing, is more developed than that of reptiles. The organs of hearing are represented by the inner, middle and outer ear. The latter consists of a deep external auditory meatus framed by skin folds and special feathers.
Birds have well developed organs of vision. Eyes of large size and complex structure, good sensitivity. Color vision is better developed than in many other animals. Birds distinguish a large number of shades. At high speed movements during the flight, vision allows you to assess the situation from a great distance, but the bird sees objects that are a few centimeters away clearly.
Nervous system
In flight, birds make complex movements, so the cerebellum, which is responsible for coordination, is large. also well developed. The forebrain hemispheres are enlarged. The internal structure of birds, their brain and nervous system is associated with the complex behavior of birds.
Most of the actions are instinctive - building a nest, forming pairs, caring for offspring. But with age, birds are able to learn. If the chicks do not feel fear of a person, then adults are afraid of people. They can distinguish a hunter from an unarmed one, and crows can understand what exactly is in a person’s hand - a stick or a gun.
Some species of birds recognize people who often feed them, can be trained and are able to imitate various sounds, including human speech.
excretory and reproductive systems
Consider the excretory and reproductive systems, their internal structure and reproduction of birds. Since the metabolism of birds is accelerated, the kidneys are large. These paired metanephric organs are divided into three lobes and are located under the dorsal walls of the pelvis. The ureters that depart from them open in the cloaca. Birds do not have a bladder. Waste products, consisting mainly of uric acid, are quickly excreted from the body.
Most birds don't. The testicles, which increase in size during the breeding season, remove the contents through the canal into the seminal vesicle located in the cloaca.
The internal structure of birds, or rather, the reproductive organs of females, has interesting features. They have developed only the left ovary and oviduct, the right ones are usually rudimentary. Most likely this is due to the lack of space for the simultaneous formation of large eggs. The oviduct departs from the ovary, which is divided into several sections: a long fallopian tube, a thin-walled and wide uterus, and a narrow vagina that opens into the cloaca. To carry out fertilization, the male presses his cloaca against the cloaca of the female.
Reproduction and care of offspring
We examined the internal structure of birds. Biology not only studies anatomy, but also analyzes the behavior of animals. Let's talk about such a complex process as reproduction and care for offspring in birds.
The breeding season begins when there is enough food. Our birds - in spring and summer. But reproduction in birds kept in captivity, for example decorative ones, is stimulated at any time of the year, increasing the amount and nutritional value of the feed.
Most small and medium birds form pairs for a season, large ones often have long alliances. They can form flocks, where temporary pairs are formed. The choice of a partner is not accidental. Males lek to attract the attention of females: spread their feathers, make special sounds, enter into fights.
Most species lay their eggs in a nest, which can be located on the ground, on trees, bushes, in hollows, minks. Eggs are protected by a strong shell, often with a camouflage color.
In brood species (poultry birds, ducks, geese, black grouse, swans), chicks emerge from the egg with open eyes and covered with down. Very quickly they begin to eat on their own and leave the nest. In nesting birds (pigeons, crows, tits, sparrows, rooks, parrots, birds of prey), cubs appear blind and naked, completely helpless.
Birds are characterized by long-term care for offspring. Birds warm and feed their chicks, protect them.
