Mammals animal habitats. What animals are mammals

Mammals are warm-blooded vertebrates. Their heart is four-chambered. Skin with a large number of glands. Hair growth is developed. The cubs are fed with milk, which is produced in the mammary glands of the female. Central nervous system highly developed. Mammals inhabit land, seas and fresh waters. All of them descended from land-based ancestors. More than 4,000 species are known.

Most mammals are four-legged animals. The body of these animals is raised high above the ground. The limbs have the same sections as the limbs of amphibians and reptiles, but are located not on the sides of the body, but under it. Such structural features contribute to more advanced movement on land. Mammals have a well-defined neck. The tail is usually small in size and... sharply separated from the body. The body is covered with hair. The hair on the body is not uniform. There is an undercoat (protects the body from cooling) and a guard (prevents the undercoat from matting and protects it from contamination). Shedding, which is inherent in mammals, is expressed in the loss of old hair and its replacement with new ones. Most animals have two molts during the year - in spring and autumn. Hair consists of horny substance. Horny formations are nails, claws, and hooves. The skin of mammals is elastic and contains sebaceous, sweat, mammary and other glands. The secretions of the sebaceous glands lubricate the skin and hair, making them elastic and resistant to wetness. Sweat glands secrete sweat, the evaporation of which from the surface of the body protects the body from overheating. Mammary glands are present only in females and function during the period of feeding the young.

Most mammals have a five-fingered limb type. However, due to adaptation to movement in different environments changes in their structure are observed. For example, in whales and dolphins, the forelimbs have changed into flippers, bats- in the wings, and in moles they look like spatulas.

The mouth of mammals is surrounded by fleshy lips. The teeth located in the mouth serve not only to hold prey, but also to grind food, and therefore they are differentiated into incisors, canines and molars. The teeth have roots with which they are strengthened in the sockets of the jaws. Above the mouth there is a nose with a pair of external nasal openings - nostrils. The eyes have well-developed eyelids. The nictitating membrane (third eyelid) is underdeveloped in mammals. Of all animals, only mammals have an external ear - the auricle.

The skeleton of mammals is similar to that of reptiles and consists of the same sections. However, there are some differences. For example, the skull of mammals is larger than that of reptiles, which is due to large sizes brain. Mammals are characterized by the presence of seven cervical vertebrae (38). The thoracic vertebrae (usually 12-15 of them) together with the ribs and sternum form a strong chest. The massive vertebrae of the lumbar region are movably articulated with each other. The number of lumbar vertebrae can be from 2 to 9. The sacral section (3-4 vertebrae) fuses with the pelvic bones. The number of vertebrae in the caudal region varies significantly and can be from 3 to 49. The girdle of the forelimbs of mammals consists of two shoulder blades with crow bones attached to them and two clavicles. The girdle of the hind limbs - the pelvis - is formed by three pairs of usually fused pelvic bones. The skeletons of the limbs of mammals are similar to those of reptiles. Most mammals have well-developed muscles of the back, limbs and their girdles.

Digestive system.

Almost all mammals bite off food with their teeth and chew it. In this case, the food mass is abundantly moistened with saliva secreted into the oral cavity by the salivary glands. Here, along with grinding, food digestion begins. The stomach of most mammals is single-chambered. In its walls there are glands that secrete gastric juice. The intestine is divided into small, large and rectal intestines. In the intestines of mammals, as well as in reptiles, the food mass is exposed to the action of digestive juices secreted by the intestinal glands, liver and pancreas. Remains of undigested food are removed from the rectum through the anus.

In all animals, the chest cavity is separated from the abdominal cavity by a muscular septum - the diaphragm. It protrudes into the chest cavity with a wide dome and is adjacent to the lungs.

Breath.

Mammals breathe atmospheric air. Respiratory system consists of the nasal cavity, larynx, trachea, lungs, characterized by a large branching of the bronchi, which end in numerous alveoli (pulmonary vesicles), intertwined with a network of capillaries. Inhalation and exhalation are carried out by contracting and relaxing the intercostal muscles and the diaphragm.

Circulatory system. Like birds, the mammalian heart consists of four chambers: two atria and two ventricles. Arterial blood does not mix with venous blood. Blood flows through the body in two circulatory circles. The mammalian heart provides intense blood flow and supplies the body tissues with oxygen and nutrients, as well as the release of tissue cells from decay products.

The excretory organs of mammals are the kidneys and skin. A pair of bean-shaped kidneys are located in the abdominal cavity on the sides of the lumbar vertebrae. The resulting urine enters the bladder through two ureters, and from there it is periodically discharged through the urethra. Sweat released from the sweat glands of the skin also removes a small amount of salts from the body.

Metabolism. A more perfect structure of the digestive organs, lungs, heart and others provides animals with high level metabolism. Due to this, the body temperature of mammals is constant and high (37-38°C).

The nervous system has a structure characteristic of all vertebrates. Mammals have a well-developed cerebral cortex. Its surface increases significantly due to the formation large quantities folds - convolutions.

In addition to the forebrain, the cerebellum is well developed in mammals.

Sense organs. Mammals have well-developed senses: olfactory, auditory, visual, tactile and gustatory. The organs of vision are better developed in animals living in open areas. Animals living in the forest have better developed senses of smell and hearing. The organs of touch - tactile hairs - are located on the upper lip, cheeks, and above the eyes. Reproduction and development of mammals. Mammals are dioecious animals. In the reproductive organs of the female - the ovaries - eggs develop, in the reproductive organs of the male - Fertilization in mammals is internal. Mature cells enter the paired oviduct, where fertilization occurs. Both oviducts open into a special organ of the female reproductive system - the uterus, which is found only in mammals. The uterus is a muscular sac, the walls of which can stretch greatly. The egg that has begun to divide attaches to the wall of the uterus, and all further development of the fetus occurs in this organ. In the uterus, the membrane of the embryo is in close contact with its wall. At the point of contact, a baby's place, or placenta, is formed. The embryo is connected to placenta umbilical cord, inside which its blood vessels pass. In the placenta, nutrients and oxygen enter and are removed from the mother's blood into the blood of the fetus through the walls of blood vessels. carbon dioxide and other waste products harmful to the embryo. Duration of embryo development in the uterus

different mammals

varies (from several days to 1.5 years). At a certain stage, the mammalian embryo has the rudiments of gills and is similar in many other characteristics to the embryos of amphibians and reptiles.

Mammals have a well-developed instinct to care for their offspring. Female mothers feed their cubs with milk, warm them with their bodies, protect them from enemies, and teach them to look for food. Caring for offspring is especially highly developed in mammals whose young are born helpless (for example, a dog, a cat). Origin of mammals. The similarity of modern mammals to reptiles, especially in the early stages of embryonic development, indicates the close relationship of these groups of animals and suggests that mammals evolved from ancient reptiles (39). In addition, even now in Australia and on the adjacent islands they live oviparous mammals, which in their structure and reproductive characteristics occupy an intermediate position between reptiles and mammals. These include representatives oviparous order, or

primal beast - platypus

and echidna. When breeding, they lay eggs covered with a durable shell that protects the contents of the egg from drying out. The female platypus lays 1 - 2 eggs in a burrow, which she then incubates. The echidna carries a single egg in a special pouch, which is a fold of skin on the ventral side of the body. The oviparous cubs that emerge from the egg are fed with milk.. In marsupials, unlike primitive animals, the development of the embryo occurs in the mother’s body, in the uterus. But the baby's place, or placenta, is absent, and therefore the baby does not stay in the mother's body for long (for example, in a kangaroo). The baby is born underdeveloped. Further development it occurs in a special fold of skin on the mother’s abdomen - the bursa. Primordial animals and marsupials are an ancient group of mammals, widespread in the past.

The importance of mammals and the protection of useful animals.

The significance of mammals for humans is very diverse. Undoubtedly harmful include many rodents that harm crops and destroy food supplies. These animals can also spread dangerous human diseases. Known harm The human economy is harmed by some predatory mammals (in our country, the wolf) that attack livestock.

The benefit of wild mammals is to obtain valuable meat, skin and fur from them, and also fat from sea animals. In the USSR, the main game animals are squirrel, sable, muskrat, fox, arctic fox, and mole.

In order to enrich the fauna (fauna is called species composition fauna of any country or region) in our country, measures are constantly being taken for acclimatization (introduction from other areas or countries) and resettlement of useful animals.

In the USSR, many species of mammals are protected by law, the hunting of which is completely prohibited.

The main orders of placental mammals:

Units	Characteristic features of units	Representatives

Insectivores	The teeth are of the same type, sharply tuberculate. The anterior end of the head is extended into a proboscis. The cerebral cortex is devoid of convolutions	Mole, hedgehog, muskrat
Chiroptera	The forelimbs are transformed into wings (formed by leathery membranes). Bones are thin and light (adaptation for flight)	Ushan, red-headed noctule
	The incisors are strongly developed, there are no fangs. They reproduce very quickly	Squirrel, beaver, mouse, chipmunk
Lagomorpha	The structure of the teeth is similar to rodents. In contrast, they have two pairs of incisors, one of which is located behind the other	Hares, rabbit
	They feed mainly on live food. The fangs are highly developed and there are carnassial teeth	Wolf, fox, bear
Pinnipeds	They spend most of their life in water. Both pairs of limbs are converted into flippers	Walrus, seal, cat
Cetaceans	They live in water. The forelimbs are transformed into flippers, the hind limbs are reduced

Animals or mammals are the most highly organized. A developed nervous system, feeding their young with milk, viviparity, and warm-blooding allowed them to spread widely throughout the planet and occupy a wide variety of habitats. Mammals are animals that live in forests (wild boars, moose, hares, foxes, wolves), mountains (rams, steppes and semi-deserts (jerboas, hamsters, ground squirrels, saigas), soil (mole rats and moles), oceans and seas ( dolphins, whales). Some of them (for example, bats) spend a significant part of their active life in the air. Today, the existence of more than 4 thousand species of animals is known. Orders of mammals, as well as the characteristic features of animals - we will talk about all this in. in this article. Let's start with a description of their structure.

External structure

The body of these animals is covered with hair (even whales have its remains). There are coarse straight hairs (hair) and fine curly hairs (undercoat). The undercoat protects the hair from contamination and matting. The coat of mammals can consist only of awns (for example, in deer) or from undercoat (as in moles). These animals shed periodically. In mammals, this changes the thickness of the fur, and sometimes the color. The skin of animals contains hair follicles, sweat and sebaceous glands and their modifications (mammary and odorous glands), horny scales (as on the tail of beavers and rats), as well as other horny formations found on the skin (horns, hooves, nails, claws). Considering the structure of mammals, we note that their legs are located under the body and provide these animals with more advanced movement.

Skeleton

They have a highly developed braincase in their skull. In mammals, teeth are located in the cells of the jaws. They are usually divided into molars, canines and incisors. The cervical spine in almost all animals consists of seven vertebrae. They are movably connected to each other, except for the sacral and two caudal ones, which, fused, form the sacrum - a single bone. The ribs articulate with the thoracic vertebrae, which are usually from 12 to 15. In most mammals, the girdle of the forelimbs is formed by paired shoulder blades and clavicles. Only a small part of the animals have crow bones preserved. The pelvis consists of two pelvic bones fused to the sacrum. The skeleton of the limbs is made of the same bones and sections as those of other representatives of four-legged vertebrates.

What sense organs do mammals have?

Mammals are animals that have ears that help them detect odors and also determine their direction. Their eyes have eyelids and eyelashes. On the limbs, belly, and head there are vibrissae - long, coarse hairs. With their help, animals sense even the slightest touch of objects.

Origin of mammals

Just like birds, mammals are descendants of ancient reptiles. This is evidenced by the similarity of modern animals with modern reptiles. It is especially evident in the early stages of embryonic development. More large quantity signs of similarity were found in them with wild-toothed lizards, which became extinct many years ago. Also, the relationship with reptiles is evidenced by the fact that there are animals that lay eggs containing many nutrients. Some of these animals have cloaca, developed crow bones and other signs indicating low organization. It's about about the primal beasts (oviparous). Let's tell you more about them.

Primal Beasts

This is a subclass of the most primitive mammals alive today. Along with the signs already mentioned, it should be noted that they do not have a constant body temperature. The mammary glands of primal beasts do not have nipples. The cubs, hatched from the eggs, lick the milk from the mother's fur.

In this subclass, one order is distinguished - Monotremes. It includes 2 species: the echidna and the platypus. These animals can today be found in Australia, as well as on the islands adjacent to it. The platypus is an animal average size. He prefers to settle along the banks of rivers and leads here semi-aquatic image life. He spends most of his time in a hole he dug in a steep bank. In the spring, the female platypus lays eggs (usually two of them) in a special burrow equipped with a nesting chamber. Echidnas are burrowing animals. Their body is covered with hard hair and spines. The females of these animals lay one egg, which they place in a pouch, a fold of skin located on the abdomen. The baby hatched from it remains in the pouch until needles appear on its body.

Marsupials

The order Marsupials includes animals that give birth to underdeveloped young, after which they carry them to term in a special pouch. Their placenta is poorly developed or does not form at all. Marsupials are distributed mainly in Australia, as well as on the islands adjacent to it. The most famous of them are the marsupial and gigantic kangaroo.

Insectivores

Insectivores are an order that unites ancient placental primitive animals: hedgehogs, shrews, moles, muskrats. They have an elongated muzzle and an elongated proboscis. Insectivores have small teeth and five-toed feet. Many of them have scent glands near the root of the tail or on the sides of the body.

Shrews are the smallest representatives of insectivores. They live in meadows, bushes, and dense forests. These animals are voracious and attack small animals. IN winter time they make passages under the snow and find insects.

Moles are animals that lead an underground lifestyle. They dig numerous holes with their front legs. The mole's eyes are poorly developed and appear as black dots. The ears are in their infancy. The short, thick coat does not have a specific direction and lies tightly to the body when moving. Moles are active all year round.

Chiroptera

Squad The bats or Chiroptera includes animals of medium and small sizes that are capable of long flight. In the subtropics and tropics they are especially numerous. These type of teeth. The most common in our country are earflaps, leather boots, and vechnitsy. They settle in the attics of houses, in tree hollows, and in caves. During the day they prefer to sleep in their shelters, and at dusk they go out to catch insects.

Rodents

This order unites a third of the mammal species inhabiting our planet today. These include squirrels, gophers, rats, mice and other animals of medium and small size. Rodents for the most part are herbivorous animals. They have highly developed incisors (two in each jaw), molars with a flat chewing surface. Rodent incisors have no roots. They constantly grow, self-sharpen and wear off when eating food. Most rodents have a long intestine with a cecum. Rodents lead wood image life (dormouse, flying squirrels, squirrels), as well as semi-aquatic (muskrats, nutria, beavers) and semi-subterranean (gophers, rats, mice). These are fertile animals. Most of them have cubs born blind and naked. This usually occurs in nests, hollows and burrows.

Lagomorpha

This order unites various pikas and pikas - animals that are similar in many ways to rodents. Main hallmark lagomorphs is specific dental system. They have 2 small incisors behind the 2 large upper ones. Hares (hares, hare) feed on the bark of bushes and young trees, and grass. They come out to feed at dusk and at night. Their cubs are born sighted, with thick fur. Unlike hares, rabbits dig deep holes. Before giving birth to naked and blind cubs, the female makes a nest from the fluff that she pulls out of her chest, as well as from dry grass.

Predatory

Representatives of this order (bears, stoats, martens, lynxes, arctic foxes, foxes, wolves) usually feed on birds and other animals. Your prey carnivorous mammal actively pursuing. The teeth of these animals are divided into incisors, molars and canines. The most developed are the canines, as well as 4 molars. Representatives of this order have a short intestine. This is due to the fact that the predatory mammal eats easily digestible and high-calorie food.

Pinnipeds

Let's move on to consider pinnipeds. Their representatives (walruses, seals) are large predatory marine mammals. The body of most of them is covered with sparse coarse hair. The limbs of these animals are modified into flippers. A thick layer of fat is deposited under their skin. The nostrils open only during inhalation and exhalation. When diving, the ear openings close.

Cetaceans

True marine mammals - whales and dolphins - are included in this order. Their body is fish-shaped. These marine mammals for the most part do not have hair on their bodies - they are preserved only around the mouth. The forelimbs have been transformed into flippers, but the hind limbs are missing. In the movement of cetaceans great importance has a powerful tail that ends in a caudal fin. It is incorrect to say that marine mammals are fish. These are animals, although in appearance they resemble fish. Representatives of cetaceans are the most large mammals. Blue whale reaches a length of 30 meters.

Artiodactyls

This order includes medium-sized and large omnivorous and herbivorous animals. Their legs have 2 or 4 toes, most of them are covered with hooves. Based on the structural features of the stomach and methods of feeding, they are divided into non-ruminant and ruminant animals. The latter (rams, goats, deer) have incisors only on the lower jaw, and the molars have a wide chewing surface. Non-ruminants have a single-chamber stomach, and their teeth are divided into molars, canines and incisors.

Odd-toed ungulates

Let us continue to describe the orders of mammals. Even-toed ungulates are animals such as horses, zebras, donkeys, tapirs, and rhinoceroses. Most of them have developed toes on their feet, on which there are massive hooves. Today, only Przewalski's horse has survived.

Primates

These are the most highly developed mammals. The order includes prosimians and apes. They have grasping five-fingered limbs, while thumb the brush is contrasted with the rest. Almost all primates have a tail. The vast majority of them live in the subtropics and tropics. They inhabit mainly forests, where they live in small family groups or in herds.

Mammals, birds, reptiles, amphibians - all of them can be described for a very long time. We have only briefly described the animals and described the existing units. The mammal family is diverse and numerous, as you have just seen. We hope that getting to know him was useful to you.

Number of species: more than 5 thousand

Habitat: inhabit all seas, oceans and continents, with the exception of Antarctica.

Features of the structure:

The body is covered with skin and is divided into a head, neck, torso, tail and four limbs with five fingers. The skin consists of the epidermis and dermis, and includes glands (sweat, sebaceous). Hair forms hair, there are guard hairs (determine the direction of fur laying), down hairs (participate in thermoregulation), and vibrissae (organs of touch). Hair may be lost (cetaceans).

Skeleton. The spine is divided into the cervical (always 7 vertebrae), thoracic (ribs form the rib cage), lumbar, sacral (all vertebrae fuse to form the sacrum) and caudal.

The skull is massive, with sutures remaining between the fused bones. The respiratory tract is separated from the oral cavity by the hard (bone) palate, which allows you to simultaneously breathe and chew food.

Digestive system. The mouth is surrounded by soft lips necessary for sucking mother's milk. Four pairs of ducts enter the oral cavity salivary glands. Teeth are differentiated - they differ in shape and structure. There are incisors, canines, premolars and molars involved in food processing. Next comes the pharynx, esophagus, stomach. The ducts of the liver and pancreas flow into the anterior section of the small intestine - the duodenum. At the border of the small and large intestines is the cecum, which can reach significant sizes in herbivores. Bacteria that process fiber develop in it. The large intestine ends at the anus.

Internal structure of a dog

Respiratory system represented by paired lungs and airways. The lungs have an alveolar structure - they consist of alveoli - thin-walled vesicles capable of stretching. Thanks to this, the lungs have a larger surface area for gas exchange. Inhalation is carried out actively; the intercostal muscles and the diaphragm, a specialized muscular septum, take part in its implementation. Air enters the lungs through the nasal openings, nasal cavity, larynx, trachea and through the two main bronchi. Exhalation occurs passively, the intercostal muscles and diaphragm relax.

Circulatory system. The heart is four-chambered, consists of two atria and two ventricles, two circles of blood circulation. The heart is located in the pericardial sac. The systemic circulation begins in the left ventricle, from which the largest artery, the aorta, departs. The aorta splits into a series large arteries, carrying oxygenated blood to the internal organs. The blood then collects in the vena cava and returns to the right atrium. The pulmonary circulation begins in the right ventricle, when the pulmonary artery departs from it, carrying blood with a high concentration of carbon dioxide to the lungs. Gas exchange occurs in the lungs, the blood gives off carbon dioxide and is saturated with oxygen, and returns through the pulmonary vein to the left atrium.

Red blood cells (erythrocytes) differ from the red blood cells of other vertebrates - they lose their nucleus and become biconcave.

Excretory system. Paired pelvic kidneys, ureters, bladder, urethra, which in placental mammals opens outwards with its own opening.

Nervous system mammals achieve exceptional development and complexity. Consists of central (brain and spinal cord) and peripheral (nerves) parts. Compared to other groups of animals, the forebrain is the most developed - the cerebral hemispheres, which are covered with a cortex. In highly organized mammals, the surface of the cortex is folded, forms grooves and convolutions, which provides higher nervous activity, complex behavior.

Sense organs. The organ of smell is the nose. The olfactory receptors are located at the back of the nasal cavity. The outer ear (pinna and external auditory canal) appears for the first time. In the middle ear there are 3 auditory ossicles - the hammer, incus and stapes, which amplify sound vibrations. To protect the eyes, eyelids with eyelashes appear. The organs of touch in the form of numerous nerve endings are located in internal organs and skin, allow you to feel pain, heat, cold, touch and pressure. The taste organs - taste buds - are located on the tongue.

Reproductive system. All representatives are dioecious animals. In males, paired testes are usually located in the scrotum, the vas deferens open into the urethra. Females have paired ovaries in the abdominal cavity, which are connected by oviducts to the uterus, a specialized muscular organ for bearing offspring.

Fertilization is internal and occurs in the upper parts of the oviduct. The fertilized egg descends into the uterus, attaches to its wall and develops into an embryo. In placental animals, the placenta is formed, through which the exchange of substances takes place between the mother and the fetus.

The cubs feed on milk, which is produced in the mammary glands of females.

Taxonomy of Mammals

There are 3 subclasses of mammals:

Oviparous (echidna, prochidna, platypus) - live in Australia and New Guinea. The female lays eggs and feeds the hatched cubs with milk, which is secreted on a special area of the skin of her abdomen - the “milky field”. Instead of the anus there is a cloaca.
Marsupials (kangaroo, koala, wombat, marsupial mice) - have very short period pregnancy. The placenta is missing. A newborn underdeveloped cub is carried in a special pouch on the stomach.
Placental or Higher mammals- the most numerous subclass. There are 17 orders of animals.

Some units:

Chiroptera (bats, fruit bats, flying foxes) – capable of flight. The forelimbs are transformed into wings. The sternum is keeled.
insectivores (hedgehogs, shrews, moles) are small animals with hemispheres almost without convolutions. The teeth are the same type.
rodents (squirrels, beavers, hamsters, rats) – incisors are highly developed and grow throughout life.
lagomorphs (hares, rabbits, pikas) - two pairs of upper incisors, one located behind the other.
predatory (bears, wolves, lynxes) – fangs are developed. Mostly carnivores.
artiodactyls (elks, deer, giraffes, antelopes) - four toes on the limb, the second and third are developed. The toes are covered with horny hooves. There are no collarbones. Complex stomach, usually consisting of several sections.
equids (horses, donkeys, tapirs, rhinoceroses) - one finger is well developed, usually with a hoof. The stomach is simple.
proboscis (elephants) - the nose and upper lip grow together into a trunk. Paired upper incisors are tusks.
primates (lemurs, monkeys, humans) – limbs of the grasping type. The brain is highly developed.

New terms: warm-bloodedness, four-chambered heart, mammary glands, lips, vibrissae, alveoli, diaphragm, convolutions of the cerebral cortex, external ear, auditory ossicles (hammer, incus and stapes), placenta.

Questions for consolidation:

Why are mammals considered the most highly organized animals among chordates?
What are the structural features of the brain in mammals?
Why hasn't a transitional form between birds and mammals been found in paleontological excavations?
What is the difference between marsupials and placental mammals?
What sense organs are most developed in different groups of mammals?
What role do mammals play in human life?

Literature:

Bilich G.L., Kryzhanovsky V.A. Biology. Full course. In 3 volumes - M.: LLC Publishing House "Onyx 21st century", 2002
Biology: A guide for applicants to universities. Volume 1. - M.: Novaya Volna Publishing House LLC: ONICS Publishing House CJSC, 2000.
Kamensky, A. A. Biology. Reference manual / A. A. Kamensky, A. S. Maklakova, N. Yu. Sarycheva // Complete course of preparation for exams, tests, testing. - M.: JSC "ROSMEN-PRESS", 2005. - 399 p.
Konstantinov V.M., Babenko V.G., Kuchmenko V.S. Biology: Animals: Textbook for 7th grade students of secondary schools / Ed. V.M. Konstantinova, I.N. Ponomareva. – M.: Ventana-Graf, 2001.
Konstantinov, V. M. Biology: animals. Textbook for 7th grade. general education schools /V. M. Konstantinov, V. G. Babenko, V. S. Kuchmenko. - M.: Ventana-Graf, 2001. - 304 p.
Latyushin, V.V. Biology. Animals: textbook. for 7th grade. general education institutions / V.V. Laktyushin, V.A. Shapkin. - 5th ed., stereotype. - M.: Bustard, 2004. - 304 p.
Pimenov A.V., Goncharov O.V. Biology manual for university applicants: Electronic textbook. Scientific editor Gorokhovskaya E.A.
Pimenov A.V., Pimenova I.N. Zoology of invertebrates. Theory. Tasks. Answers: Saratov, OJSC publishing house "Lyceum", 2005.
Taylor D. Biology / D. Taylor, N. Green, W. Stout. - M.:Mir, 2004. - T.1. - 454s.
Chebyshev N.V., Kuznetsov S.V., Zaichikova S.G. Biology: a guide for applicants to universities. T.2. – M.: Novaya Volna Publishing House LLC, 1998.
www.collegemicrob.narod.ru
www.deta-elis.prom.ua

Mammals are the most highly organized class of vertebrates. They are characterized by a highly developed nervous system (due to an increase in the volume of the cerebral hemispheres and the formation of the cortex); relatively constant body temperature; four-chambered heart; the presence of a diaphragm - a muscular septum separating the abdominal and thoracic cavities; development of cubs in the mother’s body and feeding with milk (see Fig. 85). The body of mammals is often covered with fur. The mammary glands appear as modified sweat glands. The teeth of mammals are unique. They are differentiated, their number, shape and function vary significantly among different groups and serve as a systematic feature.

The body is divided into head, neck and torso. Many have a tail. Animals have the most perfect skeleton, the basis of which is the spinal column. It is divided into 7 cervical, 12 thoracic, 6 lumbar, 3–4 sacral fused and caudal vertebrae, the number of the latter varies. Mammals have well-developed senses: smell, touch, vision, hearing. There is an auricle. The eyes are protected by two eyelids with eyelashes.

With the exception of oviparous mammals, all mammals bear their young in uterus- a special muscular organ. The cubs are born alive and are fed milk. Offspring of mammals to a greater extent needs further care than other animals.

All of these characteristics allowed mammals to gain a dominant position in the animal world. They are found all over the globe.

Appearance mammals are very diverse and determined by their habitat: aquatic animals have a streamlined body shape, flippers or fins; land dwellers have well-developed limbs and a dense body. The inhabitants air environment the front pair of limbs are transformed into wings. A highly developed nervous system allows mammals to better adapt to conditions environment, promotes the development of numerous conditioned reflexes.

The class of mammals is divided into three subclasses: oviparous, marsupials and placentals.

1. Oviparous, or primal beasts. These animals are the most primitive mammals. Unlike other representatives of this class, they lay eggs, but feed their young with milk (Fig. 90). They have preserved the cloaca - a part of the intestine into which three systems open - digestive, excretory and reproductive. Therefore they are also called monotreme. In other animals these systems are separated. Oviparous species are found only in Australia. These include only four species: echidnas (three species) and the platypus.

2. Marsupials more highly organized, but they are also characterized by primitive features (see Fig. 90). They give birth to live, but underdeveloped young, practically embryos. These tiny cubs crawl into a pouch on the mother's belly, where, feeding on her milk, they complete their development.

Rice. 90. Mammals: oviparous: 1 – echidna; 2 – platypus; marsupials: 3 – opossum; 4 – koala; 5 – dwarf marsupial squirrel; 6 – kangaroo; 7 – marsupial wolf

Australia is home to kangaroos, marsupial mice, squirrels, anteaters (nambats), marsupial bears (koalas), and badgers (wombats). The most primitive marsupials live in Central and South America. This is an opossum, a marsupial wolf.

3. Placental animals have a well developed placenta- an organ attached to the wall of the uterus and performs the function of exchanging nutrients and oxygen between the mother’s body and the embryo.

Placental mammals are divided into 16 orders. These include Insectivores, Chiroptera, Rodents, Lagomorphs, Carnivores, Pinnipeds, Cetaceans, Ungulates, Proboscideans, and Primates.

Insectivores mammals, which include moles, shrews, hedgehogs, etc., are considered the most primitive among placentals (Fig. 91). These are quite small animals. The number of teeth they have is from 26 to 44, the teeth are undifferentiated.

Chiroptera- the only flying animals among animals. They are mainly crepuscular and nocturnal animals that feed on insects. These include fruit bats, bats, noctule bats, and vampires. Vampires are bloodsuckers; they feed on the blood of other animals. Bats have echolocation. Although their eyesight is poor, due to their well-developed hearing, they catch the echo of their own squeak reflected from objects.

Rodents– the most numerous order among mammals (about 40% of all animal species). These are rats, mice, squirrels, gophers, marmots, beavers, hamsters and many others (see Fig. 91). Characteristic feature Rodents have well-developed incisors. They have no roots, grow throughout their lives, wear down, and have no fangs. All rodents are herbivores.

Rice. 91. Mammals: insectivores: 1 – shrew; 2 – mole; 3 – tupaya; rodents: 4 – jerboa, 5 – marmot, 6 – nutria; lagomorphs: 7 – brown hare, 8 – chinchilla

Close to rodents squad lagomorphs(see Fig. 91). They have a similar tooth structure and also eat plant matter. These include hares and rabbits.

To the squad predatory belongs to more than 240 species of animals (Fig. 92). Their incisors are poorly developed, but they have powerful fangs and carnassial teeth, used for tearing animal flesh. Predators feed on animal and mixed food. The order is divided into several families: canids (dog, wolf, fox), bears ( polar bear, Brown bear), felids (cat, tiger, lynx, lion, cheetah, panther), mustelids (marten, mink, sable, ferret), etc. Some predators are characterized by hibernation(the Bears).

Pinnipeds They are also predatory animals. They have adapted to life in water and have specific features: the body is streamlined, the limbs are turned into flippers. The teeth are poorly developed, with the exception of the fangs, so they only grab food and swallow it without chewing. They are excellent swimmers and divers. They feed mainly on fish. They breed on land, along seashores or on ice floes. The order includes seals, walruses, seals, sea lions etc. (see Fig. 92).

Rice. 92. Mammals: carnivores: 1 – sable; 2 – jackal; 3 – lynx; 4 – black bear; pinnipeds: 5 – harp seal; 6 – walrus; ungulates: 7 – horse; 8 – hippopotamus; 9 - reindeer; primates: 10 – marmoset; 11 – gorilla; 12 – baboon

To the squad cetaceans also include inhabitants of the waters, but, unlike pinnipeds, they never go onto land and give birth to their young in the water. Their limbs have turned into fins, and their body shape resembles fish. These animals mastered the water for the second time, and in connection with this they acquired many features characteristic of aquatic inhabitants. However, they retained the main features of the class. They breathe atmospheric oxygen through their lungs. Cetaceans include whales and dolphins. The blue whale is the largest of all modern animals (length 30 m, weight up to 150 tons).

Ungulates are divided into two orders: equids and artiodactyls.

1. TO equid include horses, tapirs, rhinoceroses, zebras, donkeys. Their hooves are modified middle fingers, the remaining fingers are reduced to to varying degrees at various types. Ungulates have well-developed molars, as they feed on plant foods, chewing and grinding them.

2. U artiodactyls the third and fourth toes are well developed, transformed into hooves, which bear the entire weight of the body. These are giraffes, deer, cows, goats, sheep. Many of them are ruminants and have a complex stomach.

To the squad proboscis belong to the largest of land animals - elephants. They live only in Africa and Asia. The trunk is an elongated nose fused with upper lip. Elephants do not have tusks, but their powerful incisors have turned into tusks. In addition, they have well-developed molars that grind plant foods. Elephants change these teeth 6 times during their life. Elephants are very voracious. One elephant can eat up to 200 kg of hay per day.

Primates combine up to 190 species (see Fig. 92). All representatives are characterized by a five-fingered limb, grasping hands, and nails instead of claws. The eyes are directed forward (primates have developed binocular vision). These are inhabitants of tropical and subtropical forests, leading both arboreal and terrestrial lifestyles. They feed on plant and animal foods. The dental apparatus is more complete and differentiated into incisors, canines, and molars.

There are two groups: prosimians and monkeys.

1. TO prosimians include lemurs, lorises, and tarsiers.

2. Monkeys are divided into broad-nosed(marmosets, howler monkeys, koatas) and narrow-nosed(macaques, monkeys, baboons, hamadryas). To the group higher narrow-nosed Great apes include gibbon, chimpanzee, gorilla, and orangutan. Humans also belong to the primates.

BASICS OF ECOLOGY