The external structure of birds reflects their ability to fly. This ability distinguishes birds from other groups of animals.
Body divisions
The body of birds has the following sections:
- torso;
- head;
- limbs;
- tail.
The body of the birds is ovoid. The streamlined shape of the body is one of the main adaptations of birds to flight in the external structure.
The head is small, with eyes, nostrils and ear holes hidden under the feathers. The auricles are absent.
No teeth. The jaws are covered with a beak, horny formation of various sizes and shapes. The shape of the beak corresponds to the method of extraction and the type of food.
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Figure: 1. Birds' beaks.
The neck is flexible, of various lengths, stretches during flight, which also increases streamlining.
Wings
The front pair of limbs is adapted for flight and is called wings. When unfolded, the wings are shaped like a Z.
Large birds have wide wings, allowing them to glide and climb in updrafts. Falcons have pointed ones for fast diving flight. Forest birds always have smaller wings than similar species that live in open spaces.
Aircraft designers have been studying the external structure of birds for a long time and use the knowledge gained in the construction of aircraft.
Legs
The legs of birds are used to move along the ground, trees and other surfaces. The length of the legs and their structure depends on the habitat. For example, in waterfowl, the legs are equipped with membranes for swimming. Running bird species have especially strong legs.
When walking, the bird rests on its fingers. The fingers are opposed so that the bird can grasp the branches of the trees. 3 fingers are located in the front and one in the back. There are claws at the ends of the fingers.
The rest of the foot bones are gathered in a tarsus, which softens the fit.
Tail
The tail has important functions:
- steering;
- inhibiting;
- is the organ of balance and balancing.
Leather
The skin is dry and thin. Birds have no skin glands, except for the coccygeal gland located at the base of the tail. This gland secretes fat to lubricate feathers and is especially developed in waterfowl species.
Feather cover
Feathers are derived from leather. Areas of skin covered with feathers are called pterilia. There are areas without feathers - apteria. The nib consists of a thick hollow shaft on which there are thin shafts - barbs. Second-order barbs with small hooks extend from each beard. All barbs adhere to each other, forming an elastic fan.
Figure: 2. The structure of the feather.
All feathers can be divided into two groups:
- downy;
- contour.
Down feathers do not have second order barbs. They underline the contour and retain heat.
The outline feathers form the outline of the body. They also reduce heat loss and also:
- form a rowing blade of the wing;
- form the tail steering plane;
- protect the bird from mechanical stress.
Depending on the location, the contour pens are divided into:
- flywheels;
- steering;
- upper tail;
- upper wing coverts and others.
Flight and tail feathers are the longest. Flight feathers form a wing blade, tail feathers are located in the tail.
The number of contour feathers in large birds is greater. So, in hummingbirds there are about 100, in gulls 5 - 6 thousand, in swans 25 thousand.
The bird is able to change the degree of feather opening and the bend of the wing, which allows it to maneuver and slow down during flight.
Figure: 3. Phases of the bird's flight.
For birds, molt, or change of feathers, is characteristic. There may be not one, but two or three molts per year. Sometimes molting is associated with the appearance of the breeding plumage of the bird.
During molting, some birds cannot fly for a certain time and are forced to hide in hard-to-reach places.
Let us summarize the characteristics of birds' adaptations to flight in the table "External structure of birds".
What have we learned?
Studying this topic in the biology of grade 7, we found out that the features of the external structure of birds: body shape, wings, feathers. These features determine the ability of birds to fly. At the same time, the birds have not lost the ability to walk and climb, have developed sense organs and are adapted to various habitats.
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Assessment of the report
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Question: Consider a stuffed bird. Find the major areas of the body. Name them. Examine the bird's head. Pay attention to its shape, dimensions. Find the beak, examine its structure. Pay attention to the location of the eyes. Find the ear cavity. Examine the body of the bird, determine its shape. Pay attention to the position of the wings and legs. Examine the external structure of the limbs, the sequence of their departments. What are the tarsus and toes covered with? Remember which animals have the same body covers. Consider the bird's tail. Write down the names of the different types of feathers located on the wings and tail, and count these feathers. Examine the set of feathers. Find an outline pen, study its structure, sketch and outline the main parts. Use a magnifying glass to examine the fan. Sketch a diagram of its structure. Consider a down feather. Sketch and sign the names of its parts. List the flight devices that are clearly visible in the external structure of birds. Fill out the results of observations in a notebook.
Consider a stuffed bird. Find the major areas of the body. Name them. Examine the bird's head. Pay attention to its shape, dimensions. Find the beak, examine its structure. Pay attention to the location of the eyes. Find the ear cavity. Examine the body of the bird, determine its shape. Pay attention to the position of the wings and legs. Examine the external structure of the limbs, the sequence of their departments. What are the tarsus and toes covered with? Remember which animals have the same body covers. Consider the bird's tail. Write down the names of the different types of feathers located on the wings and tail, and count these feathers. Examine the set of feathers. Find an outline pen, study its structure, sketch and outline the main parts. Use a magnifying glass to examine the fan. Sketch a diagram of its structure. Consider a down feather. Sketch and sign the names of its parts. List the flight devices that are clearly visible in the external structure of birds. Fill out the results of observations in a notebook.
Answers:
The body of a bird consists of a small head, usually a long neck, trunk and limbs. The upper and lower jaws, covered with horny sheaths, form a beak. The body of the birds is covered with feathers. There are claws at the ends of the toes of the hind limbs, and the lower part of the legs, the tarsus, is covered with roe shields and is devoid of feathering. The structure and functions of feathers of different parts of the body differ significantly. The base of the plumage is formed by contour feathers, consisting of a hollow core and a fan located on its sides. Distinguish between contour flight feathers, tail feathers, and coverts, in addition, there are down feathers and down.
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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 the 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, equipped with an upper and lower eyelid, as well as a nictitating 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. The 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.
Front limb 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... Part 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.
The appearance of birds reflects well their fitness for flight. As you know, the density of air is 1000 times less than the density of water, and special devices are needed to move in this environment. The compact body of the birds has an egg-shaped shape, easily streamlined by air during flight. The neck is flexible, thin and long, and as birds fly, they stretch it, also providing better air flow and reducing drag.
Birds have no teeth - they disappeared in the course of evolution. This made it possible to reduce the weight of the head, which is important for flight. On a relatively small head, a beak protrudes forward, formed by bony jaws covered with horny sheaths - the beak and mandible. The bird grabs food with its beak, its shape and structure are adapted to the acquisition and processing of certain food. At the base of the beak, there are 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 tympanic membranes. The skin is dry, devoid of glands. There is a single coccygeal gland at the base of the tail.
The body of the birds is covered with feathers. The main feathers are contour (Fig. 155). They create the contour of the bird's body, the outer outline. Contour feathers are located on certain parts of the body (pterilia), between them there are areas devoid of contour feathers (apteria). This is another device that facilitates air flow around the bird's body. The contour feathers overlap each other in tiles, protecting the bird's body and reducing its drag in flight.
Figure: 155. Arrangement of groups of feathers on the body of a bird: 1 - contour feathers; 2 - flight feathers; 3 - steering feathers
Each contour feather consists of a hard horny shaft and wide, soft and resilient fans located on its sides (Fig. 156). They are formed by thin horny plates, parallel to the stem, - barbs of the first order. Second-order beards with small hooks extend from them. These hooks interlock the barbs, forming a single fan surface.
Figure: 156. The structure of the feather: 1 - core; 2 - ochin; 3 - fan; 4 - barbs of the first order; 5 - barbs of the second order; 6 - hooks
The flight is provided by the contour feathers on the wings - flight feathers and located on the tail - tail feathers. In flight feathers, the outer fan is narrow, the inner one is wide. When the wing is raised during flight, the feathers slightly turn, forming slits, let air pass and close together into a single flying surface when the bird lowers its wings. The lower part of the feather shaft, which is located in the skin, is called the quill. Flight feathers (Fig. 157, A) are attached to the hand (primary), to the forearm (secondary) and to the shoulder (tertiary). They create the flying surface of the wing. Large primary flight feathers that form the top of the wing play a propelling role, promoting the movement of the bird forward. The tail feathers attached to the coccygeal bone regulate the direction of flight.
Figure: 157. Bird's wing: A - arrangement of feathers on the wing: 1 - primary flight feathers; 2 - secondary flight feathers; 3 - winglet; B - feather development: 1-3 - longitudinal cuts through the feather rudiments
Down feathers are under the contour feathers. They have a thin flexible shaft, barbs are devoid of hooks and do not form continuous fans. Chicks of brood birds are covered with down with a shortened shaft and a bunch of separate barbs located at its top.
Thin hair-like feathers, devoid of barbs and consisting of a thin and soft shaft, are scattered throughout the body of birds. They protrude above the surface of the contour feathers and play an important role in touch. In the corners of the mouth of swifts, swallows, nightjars there are hard bristle-like feathers. They increase the capture surface when catching insects in the air.
Birds take care of their plumage: they clean it, lubricate it with a fatty secretion of the coccygeal gland, preventing it from getting wet. The well-being of birds depends on the state of plumage: the ability to overtake prey, get away from the enemy, keep warm and the ability to fly.
Once or twice a year, birds molt, shedding old feathers, in place of which new ones grow. In most birds, feathers change gradually, and they do not lose their ability to fly. In geese, ducks, swans, flight feathers fall out at the same time, so birds for some time lose their ability to fly and stay in places inaccessible to predators. When changing plumage, birds spend a lot of energy and lose a lot of weight.
Bird feathers develop from the same epithelial rudiments as reptile scales (Fig. 157, B). Other horn formations of birds also testify to the unity of the origin of bird feathers and reptile scales. So, the legs of birds (tarsus and fingers) are covered with the same horny shields that cover the body of lizards and snakes. Sometimes, with developmental disorders, feathers appear on the site of individual scales on the legs. The horn covers of the upper and lower beaks of birds are very similar to the horn covers that cover the jaws of turtles.
Laboratory work No. 8
Theme. The external structure of the bird. Feather structure.
Goal. To study the features of the external structure of birds in connection with flight.
Equipment: tweezers, magnifying glass, stuffed bird, a set of feathers (contour, down, down).
Working process
- Consider a stuffed bird. Find the major areas of the body. Name them.
- Examine the bird's head. Pay attention to its shape, dimensions. Find the beak, examine its structure. Pay attention to the location of the eyes. Find the ear cavity.
- Examine the body of the bird, determine its shape. Pay attention to the position of the wings and legs.
- Examine the external structure of the limbs, the sequence of their departments. What are the tarsus and toes covered with? Remember which animals have the same body covers.
- Consider the bird's tail. Write down the names of the different types of feathers located on the wings and tail, and count these feathers.
- Examine the set of feathers. Find an outline pen, study its structure, sketch and outline the main parts. Use a magnifying glass to examine the fan. Sketch a diagram of its structure.
- Consider a down feather. Sketch and sign the names of its parts.
- List the flight devices that are clearly visible in the external structure of birds.
- Fill out the results of observations in a notebook.
The birds are well adapted to flight: the forelegs are turned into wings; the body has a streamlined shape and is covered with feathers that develop from the same epithelial primordia as reptile scales. The flight and tail feathers play the main role in flight.
Exercises on the covered material
- What features of the external structure of birds confirm their ability to fly?
- Describe the types of feathers and their importance in the life of birds.
- What are the common signs and differences in the structure of the integument of birds and reptiles? What does this indicate?
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 a point and a 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. A 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 forelimbs are transformed 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 and skull-to-spine joints.
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 a 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 note 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 are fused 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 flight fitness of birds. The skeleton is lightweight and durable. Lightness is provided by the pneumaticity of bones, strength - by their fusion. In the hand, the bones are fused 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.
