External structure

In animals they are well expressed: head, neck, torso and tail. On the head usually distinguish between the cranial region, located behind the eyes, and the facial, or muzzle, located in front. Eyes equipped with upper, lower and third eyelids. Unlike birds, the nictitating membrane (third eyelid) covers only half of the mammalian eye. On the sides of the head are large ears, at the end of the muzzle are paired nostrils. Mouthbordered with fleshy lips characteristic of mammals. There are usually very coarse hairs on the upper lip - vibrissae. Several of them are located above the eyes. They play the role of additional organs of touch. Under the root of the tail is the anus, and a little anterior to it - the urogenital. Females have 4-5 pairs of nipples on the ventral side of the body. The limbs are five or four-fingered, the fingers are armed with claws.

Skin

Wool, covering the body of mammals is a derivative of the skin. Distinguish hair of two genera - guard and soft - down. The skin consists of two main layers - epidermis and corium. The first is a thin stratum corneum, and the second is very thick, dense. The lower part of it forms the subcutaneous tissue.

Skeleton

The spine consists of five sections: cervical, thoracic, lumbar, sacral, and caudal. The vertebrae have flat articular surfaces characteristic of mammals and are separated by round cartilaginous discs - menisci.

The cervical region in all mammals (with very rare exceptions) contains 7 vertebrae. (Both the mouse and the giraffe have 7 cervical vertebrae). These vertebrae lack free ribs. The thoracic region contains 12-13 vertebrae, all of which are provided with ribs. The front seven pairs of ribs are connected to the sternum and are called "true ribs". The next five pairs do not reach the sternum. The lumbar spine is devoid of ribs and usually contains 6-7 vertebrae. The sacral region is formed in most mammals by four fused vertebrae. The anterior ones usually carry two processes, with the help of which the pelvis is attached. The caudal region is very variable in the number of vertebrae.

Skull it is divided into axial, consisting of bones surrounding the brain, and visceral (facial), which includes bones surrounding the mouth opening - the palate, bones of the upper and lower jaws.

Shoulder girdle It is represented only by the scapula and clavicle, and mammals do not have a crow's bone (coracoid). In fast runners, the collarbone (ungulates) usually disappears. The pelvic region consists of a pair of nameless bones, each of which is formed by the fusion of the ilium, ischium, and pubic bones. The paired limb skeleton has three typical sections. In the forelimbs, this is the shoulder, forearm and hand, and in the hind limbs, the thigh, lower leg and foot. In mammals, a rounded tendon bone appears on the hind limbs at the knee joint - the patella.

Muscular system

This system in animals reaches exceptional development and complexity. They have several hundred individual striated muscles. A feature of the muscular system of mammals is the presence of a diaphragm and the appearance of subcutaneous muscles. Diaphragm - This is a domed muscular septum that separates the chest from the abdominal. In the center, it is perforated by the esophagus. The diaphragm takes part in the acts of respiration and excrement of animals. The subcutaneous musculature is a continuous subcutaneous layer. With its help, animals can move skin areas. The same muscles take part in the formation of the lips and cheeks. In monkeys, it almost disappeared and remained only on the face. There she received an unusually strong development - this is the so-called facial muscles.

Nervous system

Brain the beast has powerfully developed hemispheres of the forebrain and cerebellum. They cover all other parts of the brain from above.

Forebrain consists of the cerebral hemispheres covered with a gray medulla - the cerebral cortex. The olfactory lobes move forward from the hemispheres. A wide jumper of white nerve fibers is located between the hemispheres.

Diencephalon has a funnel and a cross of the optic nerves, like in other classes of vertebrates. To the funnel diencephalon the pituitary gland is attached, while the pineal gland is located above the cerebellum on a long leg. Midbrain differs in very small size, in addition to the longitudinal groove, it also has a transverse groove, which is characteristic only of mammals. Cerebellum consists of an unpaired part - a worm and two lateral ones, which are very large and are usually designated as cerebellar hemispheres. Medulla has a feature that is also characteristic only of mammals. On the sides of this brain, bundles of nerve fibers are isolated, going to the cerebellum. They are called the hind legs of the cerebellum. The medulla oblongata passes into the spinal cord.

Sense organs

They are very developed in mammals, and, in accordance with the ecological specialization of one or another group, the leading role is played by smell, sight, hearing, or touch. The hearing organs in animals are especially well developed. They have bony auditory drums and large, movable outer ears.

Digestive organs

Oral cavity limited by the lips of animals. The lips take part in grasping and holding prey. The oral cavity is bounded from above by a hard bony palate. Due to this, the choanas (internal nostrils) are pushed back towards the pharynx. This allows the animals to breathe while the food is in the mouth. The sides of the oral cavity are bounded by soft, muscular cheeks, and at the bottom of the mouth is a large muscular tongue. Its functions are to perceive taste and push food while chewing under the teeth and down the throat while swallowing. The ducts of the salivary glands open into the mouth (4 paired glands - parotid, infraorbital, submandibular and sublingual). Teethdo not grow to the surface of the bone, as in previous classes, but sit in independent cells. The teeth are differentiated into incisors, canines and molars. The tooth itself consists of parts such as a crown with a working surface, the body of the tooth and its root. Throat of beasts short, the windpipe and choanae open into it. Thus, in mammals, the pharynx is the intersection of two pathways - food and respiratory. Esophagus is a simple, highly extensible muscular tube. After passing through the diaphragm, it connects to the stomach. Stomach has the appearance of a large horseshoe-shaped curved bag that lies across the body. A fat-filled peritoneum hangs from the stomach, which covers all internal organs with an apron. Liver located under the diaphragm, its streams open into the duodenum, in the loop of which the pancreas lies. Most mammals have a gallbladder. Intestines can be of different lengths, it depends on the composition of the feed. The herbivorous rabbit has a very long intestine - 15-16 times longer than the body. Its divisions are the small, large and rectum. At the beginning of the large intestine, mammals have an unpaired cecum - the cecum. The intestine opens outward with an independent anal opening.

Respiratory system

Larynx, as usual for mammals, has cricoid cartilage, in front of which is a large thyroid cartilage. The mammalian larynx is complex. On the inside of the larynx, the vocal cords are stretched. These are paired elastic folds of the mucous membrane, stretched in the laryngeal cavity and limiting the glottis. Lungs represent a pair of spongy bodies hanging freely into the chest cavity. Their internal structure is characterized by great complexity. The trachea near the lungs is divided into two bronchi. The bronchi, entering the lungs, are divided into secondary bronchi, which in turn are divided into bronchi of the third and fourth order. They end with bronchioles. The ends of the bronchioles are swollen and braided with blood vessels. These are the so-called alveoli, where gas exchange takes place.

Circulatory system

A heartanimals, like birds, have four chambers, and the left ventricle drives blood through a large circle of blood circulation and, like birds, has much thicker walls than the right one. A large vessel departs from the left ventricle - the aorta, which begins the systemic circulation. Arterial blood is supplied to all organs of the body, and venous blood is collected through the vein system. The largest of them - the posterior and two anterior vena cava - flow into the right atrium. From the right atrium, blood enters the right ventricle, from here begins a small circle of blood circulation, or, as it is also called, pulmonary. Venous blood is expelled from the right ventricle into the large pulmonary artery. This artery is divided into right and left, going to the lungs. From each lung, blood is collected in the pulmonary vein (the blood in it is arterial), both veins merge and flow into the left atrium. Further, from the left atrium, blood is poured into the left ventricle and again goes through a large circle of blood circulation.

Organs, secretions

Have mammals are a pair of bean buds located in the lumbar region. From the inner concave side of each kidney there is a ureter (thin tube) that flows directly into the bladder. The bladder opens into the urethra.

Genitals

In mammals, these are paired testes (in males) or paired ovaries (in females). Testes have a characteristic oval shape. The appendages of the testes are adjacent to them. Paired vas deferens open at the beginning of the urethra. The end parts of the vas deferens are expanded into seminal vesicles. The paired ovaries of the female have an oval-flattened shape. An oviduct is located near each ovary. One end of the oviduct opens into the body cavity, and with the opposite end, without a visible border, it passes into the uterus. The uterus in animals is two-horned, the right and left horns of the uterus open independently into the vagina. It is unpaired. With its posterior end, it gradually passes into the urethra and the bladder opens into it. Outside the vagina opens with the urogenital opening.

Embryo development

Egg cells develop in the ovary, then mature cells upon leaving the ovary into the body cavity are trapped there by the funnel of the oviduct. Due to the ciliated movements of the cilia of the tube (oviduct), the egg moves along it, and if the female is fertilized, then in the tube (usually in the first third of it) the egg merges with the sperm. The fertilized egg continues to slowly descend into the uterus and at the same time begins to break up (division of the egg into many cells). Having reached the uterus, the egg, which by that time had turned into a dense multicellular ball, is introduced into the wall. There, nutrients begin to flow to it. Pretty soon, a placenta forms around the embedded embryo. This is the shell of the fetus, very characteristic of mammals. The placenta is a spongy organ rich in blood vessels, in which the child and the mother are distinguished. The nursery consists of the villi of the embryonic membrane, and the mother's - of the uterine wall. During childbirth, the muscular layer of the uterus is greatly reduced and the children's placenta (chorion), by that time connected very slightly to the mucous membrane of the uterus, opens and leaves with the newborn in the form of a child's place.

Mammals, or Beasts, – the most highly organized vertebratesthat appeared about 160 million years ago. Just like birds, mammals - warm-blooded animalshaving a constant body temperature. They are characterized by high level of development of the nervous system, primarily the brain. Almost all mammals cubs develop in the womb, which gives birth to live babies.

Due to their active life and large numbers, animals play a huge role in nature and human economic activity... More than 5 thousand species of modern mammals are known. Up to 380 species live on the territory of Russia.

They are distributed across all continents and inhabited all living environments - air-ground, water and soil. They can be found in a wide variety of habitats. Many species of mammals have adapted to life in forests. One of them most they spend their lives in the trees squirrels, sloths, marsupial bear, or koala... Other mammals ( marten, many types of monkeys) live both on trees and on the ground. In the lower tier of the forest live bears, foxes, deer and moose.

The open spaces of the steppes and deserts were settled hamsters, gophers and jerboas.

Some types, for example moles, spend almost their entire life in the soil, leading a burrowing lifestyle.

A large group of mammals have mastered the aquatic environment. Whales and dolphins - never leave it. Seals, fur seals and walruses come out of water onto land only for breeding. Muskrat and beaver live both in water bodies and on land.

And finally, animals of a rather numerous order of bats have acquired the ability to fly. These include nocturnal insectivorous bats, as well as blood-sucking vampires.

Features of the external structure of mammals

Animal sizes different types vary greatly. For example, tiny shrewhas a length of up to four centimeters and a mass of only 1.5 grams, while a giant of oceanic expanses blue whale reaches 33 meters with a mass of 150 tons. Bush elephant - the largest of modern terrestrial vertebrates: old males reach a mass of 5 tons at a height of 4 meters.

Like other terrestrial vertebrates, the mammalian body is subdivided into head, neck, torso, paired limbs and tail... The shape and ratio of body parts in mammals is very diverse due to adaptation to life in different environments, different modes of movement, obtaining food and protecting enemies. For example, everyone is well aware of both the disproportionately long neck of a giraffe, which allows it to pluck leaves and young shoots from the crowns of trees, and the complete absence of a neck interception in cetaceans.

Most species - four-legged animals... Them the torso is lifted off the ground... Unlike reptiles, their front and hind limbs are located under the body. This gives the animals the opportunity to develop great speed. For example, in cheetahat the moment of throwing for the victim, it reaches 110 kilometers per hour.

The relatively large head is mobile due to the flexible and well-defined neck.

The mammalian mouth has upper and lower lips... Above the mouth is a nose with a pair of external nasal openings - nostril... Eyes protected upper and lower eyelids... The blinking membrane is underdeveloped. Movable on the head are clearly visible paired auricles, which are peculiar only to mammals.

The structure of the integument of mammals

Leatherrelatively thick, strong and elastic. It consists, like all vertebrates, of two layers. Outer layer - epidermis - multilayer. The lower cells of the epidermis are actively multiplying, while the upper ones are dead, keratinized and continuously slough off. The epidermis can become very thick in areas that experience constant friction during walking, such as the soles of the feet.

The inner layer of the skin is the skin itself. It is permeated with blood vessels, it contains sensitive cells that perceive pressure, pain, warmth and cold. The bottom of this layer is called subcutaneous tissue... It contains reserves of fat that are used by animals that flow into hibernation (bears, badgers). Fat layer It is also highly developed in aquatic animals such as whales and seals.

In the inner layer of the skin there are also sweat glands with excretory ducts, nerve fibers, hair follicles, the lower parts of the hair, muscles that lift the hair, sebaceous and other types of glands.

Due to the epidermis of the skin, various horny formations: hair, nails, claws, hooves, hollow horns and scales.

Hair, or coat - wool - a characteristic feature of mammals. Distinguish between thick and long hair - guard... They form the upper layer of the hairline. Under them, in the lower tier, there are thin, threadlike down hair - undercoat... A lot of air is trapped between them, which retains body heat well. The undercoat develops especially strongly towards winter.

Only a few species have completely or partially lost their hairline in the process of evolution due to certain habitat conditions. Dolphins have no hair, whales only have rudiments of lip hair.

Hedgehogs and porcupines needles represent a modified guard hair.

On different parts of the body of animals develops a small amount of very long bristle hair called vibrissae... They serve organs of touch... Nerve endings are located at the base of the hair follicle and in its walls.

Mammals, like birds and reptiles, molt... Part of the hair falls out, gradually being replaced by new ones. In animals temperate latitudes the hairline completely changes twice a year, in spring and autumn. In some species, the color of the fur changes at the same time, making the animal less noticeable in a particular season of the year. For example, white hare in winter it is covered with white fur, and by spring it changes to a gray-yellow fur coat.

In the skin of most animals, there are sebaceous, sweat, milky and odorous glands.

Sebaceous ducts open into the subcutaneous hair follicles. Their fatty secretions lubricate the growing hair, making it elastic.

Sweat gland ducts open to the surface of the skin. Sweat evaporates and cools her. Together with sweat, excess salts and a certain amount of urea are excreted from the body. Therefore, sweat glands play the role of additional excretory organs.

Milky glands are modified sweat. They develop in all female mammals without exception. Hence the name of the class - mammals. The location of the mammary glands and nipples is different. Monkeys climbing trees and bats hanging while feeding have only a pair of nipples on their chest; in insectivores and carnivores - they stretch in rows along the entire lower surface of the body. The mammary glands produce milk, which is used to feed the young.

Scent glands are modified sweat or sebaceous glands. They emit a variety of odorous secrets with the help of which animals mark their territory, recognize individuals of their own species or individuals of the opposite sex.

At the ends of mammals' fingers develop horny claws, nails, or hooves... Their formation and structure are in direct connection with the living conditions and way of life of animals. For example, horse hoof - an ideal adaptation for running in the open spaces of the steppes. Some species have horny formations on the head ( horns of antelopes, goats) or on the tail ( rat scales).

The skin plays a huge role in thermoregulation of mammals... The coat and subcutaneous layer of fat protect the body from excessive heat loss.

Summarize. Mammals- highly organized chordate warm-blooded animals with a well-developed nervous system. They are distributed throughout the world and are found on all continents, in all oceans, and on most of the existing islands. The main distinguishing feature of mammals is feeding cubs with milk.

The body is subdivided into the head, neck, torso, paired limbs, and tail. Body covered hairline... Strong development is received skin glands (sweat, greasy, milky), and horn formations.

As among plants there is the most adapted dominant group - Angiosperms, so among animals there are organisms that are distinguished by a higher specialization in the structure of external and internal organs. In this article, we will consider the features of their structure, development, reproduction and classification.

Mammals class: general characteristics

Characterization of mammals includes the designation of all their characteristics that they possess. Firstly, these are the most highly adapted animals that have managed to settle all over the planet. They are found everywhere: in the equatorial zones, steppes, deserts and even in the waters of Antarctica.

Such a wide dispersal across the planet is explained by the fact that the internal structure of mammals has its own advantages and features, which will be considered later. Their appearance also did not remain unchanged. Almost all parts of the body undergo many adaptive modifications when it comes to any particular representative.

In addition, the behavior of this class of animals is also the most highly organized and complex. This is evidenced by the fact that Homo sapiens is considered one of the orders of mammals.

The higher development of the brain allowed humans to rise above all other creatures. Today mammals play a huge role in human life. They are for him:

• power supply;
• draft force;
• pets;
• a source of laboratory material;
• agricultural workers.

The characteristics of mammals are given according to numerous studies of various sciences. But the main one is called theriology ("therios" - the beast).

Classification of mammals

There are various options for combining different types into groups. But the diversity of representatives is too great to be able to stop at any single option. Therefore, any classification can be supplemented, corrected and replaced by another.

Today, there are about 5.5 thousand species of mammals, of which 380 species live on the territory of our country. All this diversity is combined into 27 teams. The groups of mammals are as follows:

• single-pass;
• possums;
• coenolestes;
• microbiotherium;
• marsupials;
• bandicoots;
• double incisors;
• jumpers;
• golden-moles;
• aardvarks;
• damans;
• proboscis;
• sirens;
• anteaters;
• armadillos;
• lagomorphs;
• rodents;
• tupayi;
• woolly wings;
• monkey;
• insectivores;
• bats;
• equids;
• artiodactyls;
• cetaceans;
• predatory;
• pangolins.

All this inhabits all environments of life, spreads to all territories, regardless of the climate. Also, extinct organisms are not included here, since together with them the number of mammals is about 20 thousand species.

External structure of mammals

As already mentioned, in addition to the high organization inside, mammals also have a distinct outside. There are several main such signs.

1. The presence of a mandatory smooth or rough coat (in the case of a human hair).
2. Formations of the epidermis that perform a protective function - horns, hooves, claws, hair, eyelashes, eyebrows.
3. The presence of skin glands: sebaceous and sweat.
4. Seven vertebrae in the cervical spine.
5. Testes are oval-shaped.
6. Viviparity as a way of reproduction of offspring, and then taking care of it.
7. The presence of mammary glands for feeding the young, which explains the name of the class.
8. Constant body temperature or homeothermia is warm-blooded.
9. The presence of a diaphragm.
10. Differentiated teeth of various structures and types.

Thus, the external structure of mammals clearly has its own characteristics. By their totality, it is possible to identify the place of an individual in However, as always, there are exceptions. For example, the mole rat does not have a constant body temperature and is cold-blooded. And platypuses are incapable of live birth, although they are the first animals.

Skeleton and its features

The structure of the skeleton of mammals can rightfully be considered their distinctive feature. After all, only with them it is clearly divided into five main departments:

• skull;
• rib cage;
• spine;
• the belt of the lower and upper limbs;
• limbs.

In this case, the spinal column also has its own characteristics. It includes:

• cervical;
• chest;
• lumbar;
• sacral divisions.

The skull is much larger in size than that of all other representatives of the animal world. This indicates a higher organization of brain activity, mind, behavior and emotions. The lower jaw is movably attached to the skull, in addition, there is one zygomatic bone in the structure of the face.

The structure of the skeleton of mammals is especially so because the spine consists of placetal (that is, flat) vertebrae. No other representative of the fauna has such a phenomenon. In addition, the spinal cord is located inside the column by a straight cord, and its gray matter has the shape of a "butterfly".

The limbs, or rather, their skeleton, are not the same in the number of fingers, bone length and other parameters. This is due to adaptation to a certain lifestyle. Therefore, such details of the skeleton should be studied for each specific representative.

That which is located inside the animal organism and constitutes its essence is itself main part the whole individual. It is the internal structure of mammals that allows them to occupy a dominant position on land and at sea. All these features lie in the structure and functioning of each organ, and then, and the whole organism as a whole.

In general, nothing exceptional is observed in their structure. The general principles are preserved. It's just that some organs have reached their maximum development, which has left a general imprint on the perfection of the class.

The most voluminous topic for study is the structure of mammals. Therefore, the table will be the best option to reflect the general systemic organization of the internal structure of animals of this class. It can reflect the composition of organs, the main systems and the functions they perform.

The structure and functions of the systems of internal organs of a mammal

Organ system	Organs that make up it	Functions performed
Digestive	Oral cavity with tongue and teeth, esophagus, stomach, intestines and digestive glands	Capturing and grinding food, pushing it into the internal environment and complete digestion to simple molecules
Respiratory	Trachea, larynx, bronchi, lungs, nasal cavity	Gas exchange with environment, oxygenation of all organs and tissues
Circulatory	Heart, blood vessels, arteries, aorta, capillaries and veins	Blood circulation
Nervous	Spinal cord, brain and nerves extending from them, nerve cells	Providing innervation, irritability, response to all influences
Musculoskeletal	Skeleton, made up of bones and muscles that attach to them	Ensuring a constant body shape, movement, support
Excretory	Kidneys, ureters, bladder	Elimination of liquid metabolic products
Endocrine	Glands of external, internal and mixed secretion	Regulation of the whole body and many internal processes (growth, development, formation of fluids)
Reproductive system	Includes the external and internal genital organs involved in fertilization and fetal formation	Reproduction
Sense organs	Analyzers: visual, auditory, gustatory, olfactory, tactile, vestibular	Providing orientation in space, adaptation to the surrounding world

Circulatory system

The structural features of mammals consist in the presence of a four-chambered heart. This is due to the formation of a complete septum. It is this fact that stands at the head of the fact that these animals are warm-blooded, have a constant body temperature and homeostasis of the internal environment of the body as a whole.

Nervous system

The brain and spinal cord, their structure and functioning are the structural features of mammals. After all, no animal is capable of experiencing as many emotions as they are. Nature has endowed them with the ability to think, remember, think, make decisions, quickly and correctly respond to dangers.

If we talk about a person, then it is generally difficult to convey the entire scope of the superiority of reason. Animals have instincts, intuition that help them live. All this is controlled by the brain, together with other systems.

Digestive system

The internal structure of mammals allows them not only to adapt to living conditions, but also to choose their own food. So, ruminants have a special structure of the stomach, which allows them to process grass almost continuously.

The structure of the dental apparatus also varies greatly depending on the type of nutrition. In herbivores, incisors predominate, and in carnivores, canines are clearly expressed. All these are features digestive system... In addition, each species produces its own set of digestive enzymes to make it easier and more efficient to digest food.

Excretory system

The internal organs of mammals, which take part in the excretion of liquid metabolic products, are arranged according to the same principle. The kidneys process a huge volume of fluid and form a filtrate - urine. It is excreted through the ureters into the bladder, which, when filled, is emptied into the environment.

Endocrine system

All the internal structure of mammals is one and consistent in its work. However, there are two systems that are coordinators and regulators for everyone else. It:

• nervous;
• endocrine.

If the former does this by nerve impulses and irritations, then the second is wielding hormones. These chemical compounds are powerful. Almost all processes of growth, development, maturation, development of emotions, the release of glandular products, metabolic mechanisms are the result of the work of this particular system. It includes such important organs as:

• adrenal glands;
• thyroid;
• thymus;
• pituitary;
• hypothalamus and others.

Sense organs

The reproduction and development of mammals, their orientation in the surrounding world, adaptive reactions - all this would be impossible without What analyzers make them up, we have already indicated in the table. I just want to emphasize the importance and high level of development of each of them.

The organs of vision are very well developed, although not as acutely as in birds. Hearing is a very important analyzer. For predators and their prey, this is the basis and guarantee of a successful life. The victim can hear the lion's roar, being several kilometers away.

Helps to quickly change the position of the body, move and feel comfort at any turns of the body. Smell is also the key to a well-fed day. After all, most predators sense their prey by smell.

Reproduction and developmental features of mammals

Reproduction and development of mammals occurs according to all generally accepted principles. Females and males have to mate and fertilize. After that, the female bears a baby and reproduces it into the light. However, further, the difference between mammals and all other, more low-organized individuals begins. They take care of their offspring, introducing them into adult and independent life.

The number of cubs is not so great, so each of them receives care, affection and love from their parents. Man, as the pinnacle of development in the animal kingdom, also demonstrates a high degree of maternal instinct.

Outwardly, mammals are very diverse, their body structure depends on the conditions of their habitat and lifestyle. Mammals have a head, neck, torso with two pairs of limbs, and a tail. The head has a mouth, nose, eyes, ears. The mouth in mammals is limited by soft movable lips, which in childhood are involved in sucking milk, and later in the capture of food. The eyes are protected by the developed eyelids. Eyelashes are located along their edges. The blinking membrane in mammals is underdeveloped.

Unlike amphibians and reptiles, the limbs of mammals are located under the body, so it is raised above the surface of the earth.

The mammalian body is covered with strong and elastic skin. It contains the base of the hair. Distinguish between long thick guard hair and short soft fluffy hair. Particularly distinguished by hard long hair - vibrissae. As a rule, vibrissae are located on the head (the so-called "whiskers" of animals), on the lower part of the neck, on the chest. The structure of various mammalian systems is discussed in more detail in the table below.

The figure below shows the external structure of mammals (for example, a rabbit)

Features of the structure of mammals

The structure of mammals	Features of the structure of mammals
Body covers	Skin (strong and elastic, there are sebum and sweat glands); Hair cover (consists of coarse guard hairs and soft thin hairs of the undercoat that grow from hair follicles in the skin); Claws, nails, or hooves at the ends of the fingers
	1. Skull (brain and facial) 2. Spine - 7 cervical vertebrae; 12-15 thoracic (ribs are attached to them, connected in front of the sternum, forming a rib cage), 2-9 lumbar vertebrae, 3-4 sacral, caudal vertebrae (the number depends on the length of the tail) 3. Belt of the forelimbs (two shoulder blades and two collarbones) 4. Belt of the hind limbs (three pairs of fused pelvic bones) 5. Skeletons of the limbs (the structure depends on the living conditions)	1. Brain protection, food capture and chopping 2. Body support. 3. Connection of the forelimbs with the spine. 4. Connection of the hind limbs with the spine
	The muscles of the back, girdles of the limbs and limbs are especially developed.	Exercising various movements
Digestive system	Oral cavity (has teeth, tongue, salivary glands) - "pharynx -\u003e esophagus -\u003e stomach -" intestine (small and large sections and rectum, the ducts of the pancreas and liver flow into it) - "anus ...	Chopping, digesting food, absorbing nutrients into the blood
Respiratory system	Nasal cavities, larynx, trachea, two lungs. Breathing with the diaphragm.	Blood oxygenation, carbon dioxide removal
Circulatory system	Four-chambered heart, two circles of blood circulation.	Metabolism of cells with blood.
Highlighting	Kidneys (one on each side of the body) - "ureters (from each kidney) -" bladder (one) - "urethra.	Removal of excess water and decomposition products
Nervous system	1. Brain - on the cerebral hemispheres of the forebrain there is a cortex with convolutions (associated with more complex behavior than in other animals); well developed cerebellum (associated with coordination of more complex movements) 2. Spinal cord.	Motion control, unconditional and conditioned reflexes; perception and transmission of signals
Sense organs	The degree of development of each of the senses depends on the lifestyle of the animal.
Behavior	Difficult, reflexes are easily formed, providing quick adaptation to changing environmental conditions
Reproduction	All dioecious, most (except for oviparous) hatch cubs in a special body - the uterus, and the embryo is attached to the wall of the uterus by the placenta (through the umbilical cord). Pregnancy is the process of intrauterine development of the embryo. Cubs are fed with milk formed in the mammary glands (milk is a mixture of proteins, fats, carbohydrates, vitamins, mineral salts and water needed by the young). Take care of the offspring.

The figure below shows the internal structure of mammals.

FEDERAL EDUCATION AGENCY

STATE EDUCATIONAL INSTITUTION

HIGHER PUBLIC EDUCATION

"NOVOSIBIRSK STATE PEDAGOGICAL UNIVERSITY"

FACULTY OF ELEMENTARY CLASSES

Discipline: Zoology

Structural and behavioral features of mammals

Performed:

Vaschenko Elena Gennadievna

Novosibirsk 2010

Introduction

Common features of mammals

1. Features of the structure of mammals

Features of the behavior of mammals

1. Interspecies aggression

   Intraspecific aggression

Conclusion

Bibliographic list

INTRODUCTION

Zoology -a scientific discipline that studies the animal world, large component biology. According to the research objectives, zoology is divided into a number of disciplines: taxonomy, morphology, embryology, animal genetics, zoogeography, etc. Protozoology, which studies protozoa, invertebrate zoology and vertebrate zoology, are distinguished according to the research objects. The last object of research and refers theriology, studying mammals.

The emergence of mammals became possible as a result of the formation of a number of large aromorphoses, which reduced the dependence of animals on changes in the external environment. Mammals evolved from ancient reptiles at the very beginning of the Mesozoic era, i.e. earlier than birds, but the development that led to the modern richness of the forms of this class of vertebrates dates back to the Cenozoic era, after the extinction of large reptiles.

I decided to talk about mammals, because it is the most highly specialized group of land animals. Currently, there are over 4000 species of mammals.

In the first chapter of the abstract, I will give an overview of the common features of mammals that distinguish them from other animals, then I will describe the features of their structure and behavior. I will dwell on the features of the behavior of mammals in more detail, because this topic is very interesting and exciting, but it is not covered in the biology textbook.

GENERAL FEATURES OF MAMMALS

Mammals -warm-blooded vertebrates from the amniote group. As I said, this is the most highly specialized group of land animals, which is distinguished by the following progressive traits.

Highly developed central nervous system and senses... The cortex of the cerebral hemispheres, formed by gray matter, appears, which provides a high level of nervous activity and complex adaptive behavior.

Thermoregulation system, providing relative constancy of body temperature.

Live birth (except for oviparous) and feeding the cubs with mother's milk, which ensures the best safety of the offspring.

Mammal organization heightit is also expressed in the fact that all organs in them achieve the greatest differentiation, and the brain is of the most perfect structure. The center of higher nervous activity is especially developed in it - the cerebral cortex, consisting of the gray medulla. Concerning the reactions and behavior of mammals reach exceptional perfection... This is facilitated by very complex senses, especially hearing and smell. The rapid progressive development of mammals was also facilitated by the differentiation of teeth into incisors, canines and molars.

A huge role in the development of this group was played by the acquisition warm-bloodedness, that is, a constantly high body temperature. It arises due to: a) unmixed blood circulation, b) enhanced gas exchange, c) thermoregulatory devices

Unmixed circulation, as in birds, is achieved by a four-chambered heart and in animals only one (left) aortic arch is preserved. The acquisition of the alveolar structure of the lungs and the appearance of the diaphragm led to increased gas exchange. Diaphragm - This is a muscular septum that completely divides the body into two parts - the chest and abdominal. The diaphragm is involved in the act of inhaling and exhaling. Thermoregulationachieved by the appearance of the hairline and skin glands

Due to the perfection of the digestive, respiratory and circulatory systems, the entire metabolism of mammals is very intensive, which, along with high temperature the body makes them less dependent on the climatic conditions of the environment than amphibians and reptiles. The rapid progressive development of animals is also due to the fact that the highest of them have developed a live birth. The nutrition of the embryo in the womb is carried out through a special organ - placenta.After birth, the cub is fed with milk. It is secreted by special mammary glands. All this greatly increases the survival rate of the offspring.

Thanks to the height of organization and perfect psyche, mammals by the beginning of the Cenozoic era (65 million years ago) were able to displace the reptiles that had dominated on Earth until then and occupied all the main habitats.

STRUCTURAL FEATURES OF MAMMALS

External structure

In animals they are well expressed: head, neck, torso and tail. On the head usually distinguish between the cranial region, located behind the eyes, and the facial, or muzzle, located in front. Eyes equipped with upper, lower and third eyelids. Unlike birds, the nictitating membrane (third eyelid) covers only half of the mammalian eye. On the sides of the head are large ears, at the end of the muzzle are paired nostrils. Mouthbordered with fleshy lips characteristic of mammals. There are usually very coarse hairs on the upper lip - vibrissae. Several of them are located above the eyes. They play the role of additional organs of touch. Under the root of the tail is the anus, and a little anterior to it - the urogenital. Females have 4–5 pairs of nipples on the ventral side of the body. The limbs are five or four-fingered, the fingers are armed with claws.

Skin

Wool, covering the body of mammals is a derivative of the skin. Distinguish hair of two genera - guard and soft - down. The skin consists of two main layers - epidermis and corium. The first is a thin stratum corneum, and the second is very thick, dense. The lower part of it forms the subcutaneous tissue.

Skeleton

The spine consists of five sections: cervical, thoracic, lumbar, sacral, and caudal. The vertebrae have flat articular surfaces characteristic of mammals and are separated by round cartilaginous discs - menisci.

The cervical region in all mammals (with very rare exceptions) contains 7 vertebrae. (Both the mouse and the giraffe have 7 cervical vertebrae). These vertebrae lack free ribs. The thoracic region contains 12-13 vertebrae, all of which are provided with ribs. The front seven pairs of ribs are connected to the sternum and are called "true ribs". The next five pairs do not reach the sternum. The lumbar spine is devoid of ribs and usually contains 6-7 vertebrae. The sacral region is formed in most mammals by four fused vertebrae. The anterior ones usually carry two processes, with the help of which the pelvis is attached. The caudal region is very variable in the number of vertebrae.

Skull it is divided into axial, consisting of bones surrounding the brain, and visceral (facial), which includes bones surrounding the mouth opening - the palate, bones of the upper and lower jaws.

Shoulder girdle It is represented only by the scapula and clavicle, and mammals do not have a crow's bone (coracoid). In fast runners, the collarbone (ungulates) usually disappears. The pelvic region consists of a pair of nameless bones, each of which is formed by the fusion of the ilium, ischium, and pubic bones. The paired limb skeleton has three typical sections. In the forelimbs, this is the shoulder, forearm and hand, and in the hind limbs, the thigh, lower leg and foot. In mammals, a rounded tendon bone appears on the hind limbs at the knee joint - the patella.

Muscular system

This system in animals reaches exceptional development and complexity. They have several hundred individual striated muscles. A feature of the muscular system of mammals is the presence of a diaphragm and the appearance of subcutaneous muscles. Diaphragm - This is a domed muscular septum that separates the chest from the abdominal. In the center, it is perforated by the esophagus. The diaphragm takes part in the acts of respiration and excrement of animals. The subcutaneous musculature is a continuous subcutaneous layer. With its help, animals can move skin areas. The same muscles take part in the formation of the lips and cheeks. In monkeys, it almost disappeared and remained only on the face. There she received an unusually strong development - this is the so-called facial muscles.

Nervous system

Brain the beast has powerfully developed hemispheres of the forebrain and cerebellum. They cover all other parts of the brain from above.

Forebrain consists of the cerebral hemispheres, covered with a gray medulla - the cerebral cortex. The olfactory lobes move forward from the hemispheres. A wide jumper of white nerve fibers is located between the hemispheres.

Diencephalon has a funnel and a cross of the optic nerves, like in other classes of vertebrates. The pituitary gland is attached to the funnel of the diencephalon, while the pineal gland is located above the cerebellum on a long stem. Midbrain differs in very small size, in addition to the longitudinal groove, it also has a transverse groove, which is characteristic only of mammals. Cerebellum consists of an unpaired part - a worm and two lateral ones, which are very large and are usually designated as cerebellar hemispheres. Medulla has a feature that is also characteristic only of mammals. On the sides of this brain, bundles of nerve fibers are isolated, going to the cerebellum. They are called the hind legs of the cerebellum. The medulla oblongata passes into the spinal cord.

Sense organs

They are very developed in mammals, and, in accordance with the ecological specialization of one or another group, the leading role is played by smell, sight, hearing, or touch. The hearing organs in animals are especially well developed. They have bony auditory drums and large, movable outer ears.

Digestive organs

Oral cavity limited by the lips of animals. The lips take part in grasping and holding prey. The oral cavity is bounded from above by a hard bony palate. Due to this, the choanas (internal nostrils) are pushed back towards the pharynx. This allows the animals to breathe while the food is in the mouth. The sides of the oral cavity are bounded by soft, muscular cheeks, and at the bottom of the mouth is a large muscular tongue. Its functions are to perceive taste and push food while chewing under the teeth and down the throat while swallowing. The ducts of the salivary glands open into the mouth (4 paired glands - parotid, infraorbital, submandibular and sublingual). Teethdo not grow to the surface of the bone, as in previous classes, but sit in independent cells. The teeth are differentiated into incisors, canines and molars. The tooth itself consists of parts such as a crown with a working surface, the body of the tooth and its root. Throat of beasts short, the windpipe and choanae open into it. Thus, in mammals, the pharynx is the intersection of two pathways - food and respiratory. Esophagus is a simple, highly extensible muscular tube. After passing through the diaphragm, it connects to the stomach. Stomach has the appearance of a large horseshoe-shaped curved bag that lies across the body. A fat-filled peritoneum hangs from the stomach, which covers all internal organs with an apron. Liver located under the diaphragm, its streams open into the duodenum, in the loop of which the pancreas lies. Most mammals have a gallbladder. Intestines can be of different lengths, it depends on the composition of the feed. The herbivorous rabbit has a very long intestine - 15-16 times longer than the body. Its divisions are the small, large and rectum. At the beginning of the large intestine, mammals have an unpaired cecum - the cecum. The intestine opens outward with an independent anal opening.