List and description of the main orders of the class Mammals. What animals are mammals. Presentation on the theme of mammals in elementary school Mammal group animals examples

Their natural habitat. The buildings look like rock formations with numerous burrows and crevices. Therefore, bats can find shelter in basements and attics, foxes are able to dig a hole under a fence, raccoons like to settle in ventilation ducts (moreover, both foxes and raccoons look for food in garbage cans).

A golf course resembles a clearing in a forest, steppe or meadow. Here you can look for signs of the habitation of skunks, deer, moles and rabbits. In the suburbs, there are usually not too many trees, but birdhouses and special houses for bats forest inhabitants can settle: flying squirrels, mice, the bats.

Forests and groves

Once forests covered most America east of the Appalachian Range, but by 1900 settlers had cleared the area all the way to New England. The forests now growing on this land have recently been planted. Many mammals characteristic of these places depended on the composition of forest species. Some disappeared completely, while others, such as bats, became much less common. Similar changes have taken place in Europe and Russia.

Seals, sea lions and walruses during the period of the appearance of offspring crawl out onto land, forming large colonies and returning every year to the same place. If you see them, then try not to disturb them. Seals sometimes come out on land and just to relax in the sun.

Many mammals are partially aquatic, living near lakes, streams, or ocean shorelines (eg seals, sea lions, walruses, otters, muskrats, and many others). Whales and dolphins () are completely aquatic and can be found in all and some rivers. Whales can be found in polar, temperate and tropical waters, both near the coast and in the open ocean, and from the surface of the water to a depth of more than 1 kilometer.

The habitat of mammals is also characterized by various climatic conditions. For example, the polar bear lives calmly at sub-zero temperatures, while lions and giraffes need a warm climate.

Mammal groups

Baby kangaroo in mother's pouch

There are three main groups of mammals, each of which is characterized by one of the main features of embryonic development.

• Monotremes or oviparous (Monotremata) lay eggs, which is the most primitive reproductive feature in mammals.
• marsupials (Metatheria) are characterized by the birth of underdeveloped young after a very short gestation period (8 to 43 days). Offspring are born at a relatively early stage of morphological development. The cubs are attached to the mother's nipple and sit in the bag, where their subsequent development takes place.
• Placental (Placentalia) are characterized by long gestation (pregnancy), during which the embryo interacts with its mother through a complex embryonic organ - the placenta. After birth, all mammals depend on the milk of their mothers.

Lifespan

Just as mammals vary greatly in size, so does their lifespan. As a rule, small mammals live less than larger ones. Bats ( Chiroptera) are an exception to this rule - these relatively small animals can live for one or more decades in vivo, which is significantly longer than the lifespan of some larger mammals. Life expectancy ranges from 1 year or less to 70 years or more in the wild. bowhead whales can live over 200 years.

Behavior

The behavior of mammals varies significantly among species. Since mammals are warm-blooded animals, they require more energy than cold-blooded animals of the same size. Activity indicators of mammals reflect their high energy requirements. For example, thermoregulation plays an important role in the behavior of mammals. Those animals that live in colder climates need to keep their bodies warm, while mammals that live in hot and dry climates need to cool down to keep their bodies hydrated. Behavior is an important way for mammals to maintain physiological balance.

There are species of mammals that exhibit almost every type of lifestyle, including vegetative, aquatic, terrestrial, and arboreal. Their ways of moving around their habitat are varied: mammals can swim, run, fly, glide, and so on.

Social behavior also varies considerably. Some species can live in groups of 10, 100, 1000 or more individuals. Other mammals are generally solitary except when mating or rearing offspring.

The nature of activity among mammals also covers the full range of possibilities. Mammals can be nocturnal, diurnal, or crepuscular.

Nutrition

Most mammals have teeth, although some animals, such as baleen whales, have lost them during evolution. Since mammals are widely distributed in various conditions habitats, they have a wide range of feeding habits and preferences.

Marine mammals eat various types mining, including small fish, crustaceans and sometimes other marine mammals.

Among land mammals there are herbivores, omnivores and carnivores. Each individual takes its place in.

Being warm-blooded, mammals require much more food than cold-blooded animals of the same size. Thus, a relatively small number of mammals may have big influence on the population of their food preferences.

reproduction

Mammals tend to reproduce sexually and have internal fertilization. Almost all mammals are placental (with the exception of oviparous and marsupials), that is, they give birth to live and developed young.

Generally, most mammalian species are either polygynous (one male mates with several females) or promiscuous (both males and females have multiple matings in a given breeding season). Since females carry and nurse their offspring, it often happens that male mammals can produce many more offspring during the mating season than females. As a consequence, the most common mating system in mammals is polygyny, with relatively few males fertilizing many females. At the same time, a large number of males do not participate in reproduction at all. This scenario sets the stage for intense competition between males among many species, and also allows females to choose a stronger mating partner.

Many mammalian species are characterized by sexual dimorphism, whereby males are better able to compete for access to females. Only about 3% of mammals are monogamous and only mate with the same female each season. In these cases, males may even participate in the upbringing of offspring.

As a rule, the reproduction of mammals depends on their habitat. For example, when resources are scarce, males spend their energy breeding with a single female and provide food and protection for the young. If, however, resources are plentiful and the female can ensure the well-being of her offspring, the male goes to other females. In some mammals, polyandry is also common, when a female has bonds with several males.

In most mammals, the embryo develops in the uterus of the female until it is fully formed. The born cub is fed with mother's milk. In marsupials, the embryo is born underdeveloped, and its further development takes place in the mother's pouch, as well as feeding with mother's milk. When the calf reaches full development, it leaves the mother's pouch, but can still spend the night in it.

Five species of mammals that belong to the order Monotremes actually lay eggs. Like birds, representatives of this group have a cloaca, which is a single opening that serves for emptying and reproduction. The eggs develop inside the female and receive the necessary nutrients for several weeks before laying. Like other mammals, monotremes have mammary glands and females feed their offspring with milk.

Offspring need to grow, develop and maintain optimum temperature body, but feeding the young with nutrient-rich milk takes a lot of energy from the female. In addition to producing nutritious milk, the female is forced to protect her offspring from all sorts of threats.

In some species, the cubs stay with their mother for a long time and learn the necessary skills. Other species of mammals (such as artiodactyls) are already born quite independent and do not need excessive care.

Role in the ecosystem

The ecological roles or niches filled by more than 5,000 mammal species are varied. Each mammal takes its place in the food chain: there are omnivores, carnivores and their victims - herbivorous mammals. Each species, in turn, affects. Due in part to their high metabolic rates, the impact that mammals have on nature is often disproportionate to their abundance. Thus, many mammals may be carnivores or herbivores in their communities, or play an important role in seed dispersal or pollination. Their role in the ecosystem is so diverse that it is difficult to generalize. Despite their low species diversity, compared to other groups of animals, mammals have a significant impact on the global.

Significance for a person: positive

Mammals are important to mankind. Many mammals have been domesticated to provide humankind with foods such as meat and milk (such as cows and goats) or wool (sheep and alpacas). Some animals are kept as service or pets (eg dogs, cats, ferrets). Mammals are also important to the ecotourism industry. Think of the many people who go to zoos or all over the world to see animals such as whales or whales. Mammals (eg bats) often control pest populations. Some animals, such as rats and mice, are vital to medical and other scientific research, and other mammals can serve as models in human medicine and research.

Significance for a person: negative

plague epidemic

Some species of mammals are believed to have a detrimental effect on human interests. Many species that eat fruits, seeds, and other types of vegetation are crop pests. Carnivores are often considered a threat to livestock or even human life. Mammals common in urban or suburban areas can become a problem if they cause damage to cars when they get on the road or become household pests.

Several species coexist well with humans, including domesticated mammals (eg, rats, house mice, pigs, cats, and dogs). However, as a result of the intentional or unintentional introduction of invasive (non-native) species into ecosystems, they have negatively affected the local biodiversity of many regions of the world, especially the endemic biota of islands.

Many mammals can transmit diseases to humans or livestock. Bubonic plague is considered the most famous example. This disease is spread by fleas carried by rodents. Rabies is also a significant threat to livestock and can also kill people.

Security

Overexploitation, habitat destruction and fragmentation, introduction invasive species other anthropogenic factors threaten the mammals of our planet. Over the past 500 years, at least 82 species of mammals are considered extinct. About 25% (1,000) of mammal species are currently listed on the IUCN Red List, as they are at various risks of extinction.

Species that are rare or require large ranges are often at risk due to habitat loss and fragmentation. Animals known to threaten people, livestock or crops may die at the hands of humans. Those species that are exploited by humans for quality (for example, for meat or fur), but not domesticated, are often depleted to critically low levels.

Finally, it negatively affects flora and fauna. The geographic ranges of many mammals change due to changes in temperature. As temperatures rise, which is especially noticeable in the polar regions, some animals are unable to adapt to new conditions, and therefore may disappear.

Protective measures include tracking habitats and carrying out a set of measures to protect mammals.

Mammals are warm-blooded vertebrates. Their heart is four-chambered. Skin with large quantity glands. Developed hairline. Cubs are fed with milk, which is produced in the mammary glands of the female. The central nervous system is highly developed. Mammals inhabit land, seas and fresh water. All of them descended from terrestrial ancestors. More than 4000 species are known.

Most mammals are quadrupeds. 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 a more perfect movement on land. Mammals have a well-defined neck. The tail is usually small and. sharply separated from the body. The body is covered with hair. Hair on the body is not uniform. Distinguish between undercoat (protects the body from cooling) and awn (does not allow the undercoat to fall off, protects it from pollution). The molt 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 is made up of horny matter. Horny formations are nails, claws, hooves. The skin of mammals is elastic and contains sebaceous, sweat, milk and other glands. The secretions of the sebaceous glands lubricate the skin and hair, making them elastic and non-wettable. Sweat glands secrete sweat, the evaporation of which from the surface of the body protects the body from overheating. The mammary glands are present only in females and function during the period of feeding the cubs.

Most mammals have five-fingered limbs. However, in connection with the adaptation to movement in different environment there are changes in their structure. For example, in whales and dolphins, the forelimbs have changed into flippers, in bats - into 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 which they are fixed in the sockets of the jaws. Above the mouth 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 outer ear - the auricle.

The skeleton of mammals is similar to that of reptiles and consists of the same sections. However, there are also some differences. For example, the skull in mammals is larger than in reptiles, which is associated with 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. Massive lumbar vertebrae are movably articulated with each other. The number of lumbar vertebrae can be from 2 to 9. sacral department(3-4 vertebrae) grows together with the bones of the pelvis. The number of vertebrae of the caudal region varies considerably and can be from 3 to 49. The belt of the forelimbs of mammals consists of two shoulder blades with crow bones attached to them and two clavicles. The belt 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 belts.

Digestive system.

Almost all mammals bite off food with their teeth and chew it. At the same time, the food mass is abundantly moistened with saliva secreted into the oral cavity by the salivary glands. Here, along with grinding, digestion of food begins. The stomach in most mammals is single-chambered. In its walls are glands that secrete gastric juice. The intestine is divided into small, large and rectum. 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. The 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. The 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), braided with a network of capillaries. Inhalation and exhalation are carried out by contraction and relaxation of 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 circles of blood circulation. The mammalian heart provides intensive blood flow and supply of 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 buds is located in abdominal cavity on the sides of the lumbar vertebrae. The resulting urine passes through the two ureters to the bladder, and from there urethra periodically released. Sweat released from the sweat glands of the skin also removes a small amount of salt from the body.

Metabolism. A more perfect structure of the digestive organs, lungs, heart and others provides in animals 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 is significantly increased due to the formation a large number folds - convolutions. In addition to the forebrain, the cerebellum is well developed in mammals.

Sense organs. Mammals have well-developed sense organs: 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 organs of smell and hearing. The organs of touch - tactile hairs - are located on upper lip, cheeks, 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 - testicles - spermatozoa. Fertilization in mammals is internal. Mature cells enter the paired oviduct, where they are fertilized. Both oviducts open into a special organ of the female reproductive system - the uterus, which only mammals have. The uterus is a muscular bag, the walls of which are capable of greatly stretching. The ovum that has begun to divide is attached to the wall of the uterus, and all further development of the fetus occurs in this organ. In the uterus, the shell of the embryo is in close contact with its wall. At the point of contact, a child's place, or placenta, is formed. The fetus is connected to the placenta by the umbilical cord, inside which its blood vessels pass. In the placenta, through the walls of blood vessels from the mother's blood, nutrients and oxygen enter the blood of the fetus and carbon dioxide and other waste products harmful to the fetus are removed. The duration of the development of the embryo in the uterus in different mammals is different (from several days to 1.5 years). At a certain stage, the embryo of mammals has the rudiments of gills and, in many other ways, is similar to the embryos of amphibians and reptiles.

Mammals have a well-developed instinct for caring for offspring. Female mothers feed their cubs with milk, warm them with their bodies, protect them from enemies, and teach them to look for food. Care for offspring is especially strongly developed in mammals, whose cubs are born helpless (for example, a dog, a cat).

Origin of mammals.

The similarity of modern mammals with reptiles, especially in the early stages of embryonic development, indicates the close relationship of these groups of animals and suggests that mammals are descended from ancient reptiles (39). In addition, even now in Australia and on the islands adjacent to it live oviparous mammals, which, in their structure and characteristics of reproduction, occupy an intermediate position between reptiles and mammals. These include representatives detachment of oviparous, or the first animals, the platypus and the echidna.

When breeding, they lay eggs covered with a strong 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. Echidna bears a single egg in a special bag, representing a fold of skin on the ventral side of the body. The hatchlings that hatch from the egg are fed with milk.

Order Marsupials. They include kangaroos, marsupial wolf, marsupial bear koala, marsupial anteaters. In marsupials, unlike the first animals, the development of the embryo occurs in the mother's body, in the uterus. But the placenta, or placenta, is absent, and therefore the cub does not stay long in the mother's body (for example, in a kangaroo). The cub is born underdeveloped. Its further development occurs in a special fold of skin on the mother's abdomen - a bag. First animals and marsupials - ancient group mammals, widespread in the past.

The importance of mammals and the protection of useful animals.

The importance of mammals for humans is very diverse. Certainly harmful are many rodents that damage crops and destroy food supplies. These animals are also distributors of dangerous human diseases. Known harm to the human economy is caused by some predatory mammals(in our country - a wolf), attacking livestock.

The benefits of wild mammals are in obtaining 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 (the species composition of the animal world of a country or region is called fauna), acclimatization (introduction from other regions or countries) and the resettlement of useful animals are constantly carried out in our country.

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

The main orders of placental mammals:

Detachments	Characteristic signs 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, desman
Bats	The forelimbs are transformed into wings (formed by leathery membranes). Bones thin and light (adaptation for flight)	Ushan, red evening
	The incisors are strongly developed, there are no fangs. Reproduce very quickly	Squirrel, beaver, mouse, chipmunk
Lagomorphs	The structure of the teeth are 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. Strongly developed fangs and carnivorous teeth	wolf, fox, bear
pinnipeds	Most of their lives are spent 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

Class characteristic.mammals- warm-blooded (homeothermic) amniotes; the body is covered with hair; viviparous; babies are fed with milk. Have a large brain; its anterior section (hemisphere) has a "new cortex" - neopallium - from the gray medulla; it provides a high level nervous activity and complex adaptive behavior.

The organs of smell, sight, and hearing are well developed. There is an external ear; There are three bones in the middle ear: the hammer, anvil, and stirrup. Bats, dolphins, and some other mammals use ultrasonic echolocation to navigate. Skin with numerous sebaceous and sweat glands, some of which have been converted into lactiferous and odorous glands. The skull is synapsid, articulated with the spine by two condyles; heterodont teeth sit in the alveoli; the lower jaw is only dentary. They breathe with lungs having an alveolar structure. The body cavity is divided by the diaphragm into thoracic and abdominal sections. The intestinal tube becomes more complicated, sometimes a multi-chambered stomach is formed, the caecum increases. Herbivorous animals develop symbiotic digestion.

African elephant(Loxodonta africana)

The heart is four-chambered, two circles of blood circulation, only the left aortic arch is preserved; erythrocytes are non-nuclear. The kidneys are metanephric. Widespread throughout; inhabit all environments, including soil (soil), water bodies and surface layers of the atmosphere. Very influential members of almost all biocenoses. They are important for humans: farm animals, commercial species, keepers of human and domestic animal diseases, pests of agriculture and forestry, etc.

Origin and evolution of mammals. Mammals descended from theromorphic (animal-like) reptiles that appeared back in the Upper Carboniferous, which had a number of primitive features: amphicoelous vertebrae, movable cervical and lumbar ribs, and small brain sizes. At the same time, their teeth sat in the alveoli and began to differentiate into incisors, canines, and molars. Many animal-like reptiles had a secondary bony palate, and the occipital condyle was two or three-parted; they formed a double articulation of the lower jaw with the skull: through the articular and square and through the dentary and squamous bones. In this regard, the dentary in the lower jaw increased, while the square and articular, on the contrary, decreased; while the latter did not grow to the lower jaw. Theromorphic reptiles differed little from their ancestors - the cotylosaurs that lived in humid biotopes - and retained many features of the organization of amphibians. This may explain the presence of skin with numerous glands and other features in mammals.

For a long time during the Permian and most of the Triassic periods, theromorphic reptiles, having formed a number of groups of herbivorous, predatory and omnivorous species, flourished in land biocenoses and died out only in jurassic, unable to withstand competition with the progressive archosaurs that had appeared by that time (see above the origin of reptiles). Relatively small theromorphs, apparently, were pushed back by competitors and enemies to less favorable biotopes (swamps, thickets, etc.). Life in such conditions required the development of sensory organs and the complication of behavior, the strengthening of communication between individuals. In these groups of medium-sized and less specialized animal-toothed (theriodont) reptiles, a new line of development began. the upper olfactory shell, which provided heating and humidification of the inhaled air; the appearance of three-cusp teeth; an increase in the cerebral hemispheres of the forebrain, the formation of soft lips, which opened up the possibility of sucking milk by the cubs; the appearance of an additional articulation of the lower jaw with the skull, accompanied by a reduction of the quadrate and articular bones, etc. However, the assumptions of G. Simpson (1945, 1969) about the polyphyletic (from different groups of theromorphic reptiles) origin of individual subclasses of mammals were not justified.

Cheetah(Acinonyx jubatus)

It can be considered proven that both subclasses of mammals arose in the Triassic period from one initial group of animal-like reptiles with primitive three-tuberculate teeth - carnivorous cynodonts (Tatarinov, 1975). By this time, they had acquired a secondary palate that strengthened the jaw apparatus, a differentiated dentition, and a physique reminiscent of mammals (in particular, the setting of paired limbs under the body). Apparently, they had a diaphragm separating the body cavity, and other signs of mammals. Known ancient mammal- erythroterium - was small, smaller than a rat. The ways and time of the further formation and evolution of the two subclasses of mammals remain unclear.

Upper Triassic mammals are already divided into two branches (subclass), in each of which a double articulation of the jaws arose and the formation of the dental system and the formation of "occlusion" - a close closure of the teeth of the upper jaw with the lower, increasing the possibility of machining food. The first branch - a subclass of the first beasts - Prototheria known from deposits Triassic period the remains of small animals with three-pointed molars - Triconodontia. From them originated multituberous - Multituberculata(extinct at the end Cretaceous) and single-pass - Monotremata, currently represented by the platypus and echidnas. The second branch - real animals - Theria- gave rise to the vast majority of modern mammals (infraclasses - marsupials - Metatheria and placental - Eutheria).

It took a long time for the formation of a new class - mammals. Brain development also progressed slowly.

In theromorphic reptiles, the most developed part of the brain was the cerebellum. On this basis, cynodonts (as well as all animal-like reptiles) should be called "metencephalic animals". On the way to mammals, there was a gradual increase in the forebrain. In this, mammals differ sharply from theromorphic reptiles, earning the name telencephalic group.

For two thirds of its geological history mammals remained small creatures that looked like rats and did not play a significant role in nature. Their rapid progress in the Cenozoic, obviously, was associated not only with the successive accumulation of many adaptations that led to the formation of warm-bloodedness and an increase in the energy level (energy of vital activity, according to A. N. Severtsov), live birth and feeding of young with milk, but especially with the development of organs feelings, central nervous system(cerebral cortex) and the hormonal system. Taken together, this led not only to the improvement of the organism as an integral system, but also ensured the complication of behavior. The consequence was the development of connections between individuals and the formation of complex dynamic groupings. Such "socialization" of relationships in mammalian populations (as in birds) has created new opportunities in the struggle for existence and position in biocenoses.

Alpine cycle of mountain building at the end of the Mesozoic and at the beginning cenozoic era changed the face of the earth; high ridges rose, the climate became more continental, its seasonal contrasts increased, and it became colder on a significant part of the Earth's surface. Under these conditions, the modern flora was formed with the dominance of angiosperms, especially dicotyledonous plants, while the flora of cycads and gymnosperms became poorer. All this put large and infertile herbivorous and predatory reptiles in a difficult position, while smaller warm-blooded birds and mammals more easily adapted to change. Switching to a diet of small animals and high-calorie fruits, seeds and vegetative parts angiosperms, they intensively multiplied, successfully competing with reptiles. The result was the extinction of the reptiles discussed above; it completed mesozoic era, and the wide adaptive radiation of mammals and birds opened the Cenozoic era.

bottlenose dolphin or bottlenose dolphin(Tursiops truncatus)

In the Jurassic period, 6 orders of mammals were formed, and in the Paleocene (60 million years ago) there were already at least 16 orders, 9 of which - Monotremata, Marsupialia, Insectivora, Dermoptera, Primates, Edentata, Lagomorpha, Rodentia, Carnivora- have survived to the present day. First marsupials found in Upper Cretaceous deposits North America and Lower Tertiary layers of America and Eurasia; some species live in America and in our time. The preservation of a variety of marsupials in Australia is explained by the fact that it separated from other continents even before the placental settlement. Emerging, apparently, not later than marsupials, placental mammals at first developed slowly. But their main advantage - the birth of more formed cubs, which reduced infant mortality, made it possible to displace marsupials almost everywhere. In our time, they form the core of the mammalian fauna and are represented by a wide variety of life forms that have occupied almost all landscapes of the Earth.

A variety of adaptations of mammals contributed to the development of not only land, but also fresh and marine waters, soil, and air. They ensured an unusually wide use of food resources compared to other vertebrates - the range of nutrition of mammals is more diverse than the composition of the food of other terrestrial and aquatic vertebrates, which increases the importance of mammals in the biosphere and their role in the life of various biocenoses.

Mammal class system and review of modern groups. The class Mammals is divided into two subclasses and includes 19 modern and 12-14 extinct orders. There are 257 families (139 extinct) and about 3000 genera (about 3/4 extinct); about 6,000 species have been described, of which 3,700-4,000 are living. In the modern fauna, there are approximately 2 times less species of mammals than birds (8600). At the same time, a more significant role of mammals (besides humans) in the life of the biosphere is obvious. This can be explained by the fact that the ecological niches of mammalian species are, on average, wider than those of birds.

Accordingly, their biomass (the total mass of all individuals in a given biocenosis) is usually higher than that for birds.

Relationships between orders of placental mammals have not been sufficiently clarified. Undoubtedly, the order of insectivores (remains from the Cretaceous period) is close to the ancestral forms; it has survived to the present day and, in addition, gave rise to woolly wings,

Quite difficult: different scientists have their own views on which animals belong to a particular order, superorder, clade, group, and all other complex terms that biologists use when unraveling the branches of the tree of life. To simplify the classification a bit, in this article you will discover the alphabetical list and characteristics of the orders of mammals, which most scientists agree with.

Afrosoricidae and insectivores

The order of mammals formerly known as insectivores ( insectivora), has undergone major changes in recent times, dividing into two new orders: insectivores ( Eulipotyphia) and afrosoricides ( Afrosoricida). In the last category are two very obscure creatures: bristly hedgehogs from South Africa and golden moles from Africa and Madagascar.

common tenrec

To the squad Eulipotyphia includes hedgehogs, flint-toothed, shrews and moles. All members of this order (and most afrosoricides) are tiny, narrow-nosed, insectivorous animals whose bodies are covered with thick fur or spines.

Armadillos and edentulous

Nine-banded armadillo

The ancestors of armadillos and edentulous first arose in South America about 60 million years ago. Animals from these orders are characterized unusual shape vertebrae. Sloths, armadillos and anteaters, which belong to the superorder edentulous ( Xenarthra) have the most sluggish metabolism of any other mammal in existence. Males have internal testicles.

Today, these animals are at the edge of the mammal class, but at the time, they were among the largest organisms on Earth, as evidenced by the five-ton prehistoric sloth Megatherium, as well as the two-ton prehistoric armadillo Glyptodon.

rodents

spiny mouse

The most numerous order of mammals, consisting of more than 2000 species, includes squirrels, dormice, mice, rats, gerbils, beavers, ground squirrels, kangaroo jumpers, porcupines, striders and many others. All of these tiny, furry animals have teeth: one pair of incisors in the upper and lower jaws? and a large gap (called a diastema) located between the incisors and molars. The incisors grow continuously and are constantly used to grind food.

hyraxes

Daman Bruce

Hyraxes are thick, short-legged, herbivorous mammals, which are a bit like a hybrid of a domestic cat and a rabbit. There are four (according to some sources, five) types of hyraxes: tree hyrax, western hyrax, Cape hyrax and Bruce's hyrax, all of which come from Africa and the Middle East.

One of the strangest features of hyraxes is their relative lack of internal temperature regulation; they are warm-blooded, like all mammals, but at night they gather in groups to keep warm, and during the day they warm up in the sun for a long time, like reptiles.

Lagomorphs

Even after centuries of study, scientists are still not sure what to do with hares, rabbits and pikas. These small mammals look like rodents, but have some important differences: Lagomorphs have four, not two, incisors in the upper jaw, and they are also strict vegetarians, while mice, rats and other rodents, as a rule,.

Lagomorphs can be identified by their short tails, long ears, slit-like nostrils that they can close, and (in some species) have a pronounced tendency to move by hopping.

Caguana

Malayan woolly wing

Never heard of kaguans? And this wave is possible, because on our planet there are only two living species of woolly wings that live in the dense jungles of Southeast Asia. Kaguanas have a wide skin membrane that connects all the limbs, tail and neck, which allows them to glide from one tree to another, at a distance of about 60 m.

Ironically, molecular analysis has shown that caguanas are the closest living relatives of our own order of mammals, the primates, but their rearing behavior is most similar to marsupials!

cetaceans

The detachment includes almost a hundred species and is divided into two main suborders: toothed whales (including sperm whales, beak-winged, killer whales, as well as dolphins and porpoises) and baleen whales (smooth, gray, dwarf and striped whales).

These mammals are characterized by their flipper-like forelimbs, reduced hind limbs, streamlined bodies, and a massive head that extends into a "beak". The blood of cetaceans is unusually rich in hemoglobin, and this adaptation allows them to stay submerged for long periods of time.

Odd-toed ungulates

Compared to their equivalent artiodactyl cousins, they are a rare order consisting exclusively of horses, zebras, rhinos and tapirs - only about 20 species. They are characterized by an odd number of fingers, as well as a very long intestine and a single-chamber stomach containing specialized ones that help digest tough vegetation. Oddly enough, according to molecular analysis, equid mammals may be more closely related to carnivores (predator order) than to artiodactyl mammals.

Monotreme or oviparous

These are the most bizarre mammals on our planet. Two families belong to: platypus and echidna. The females of these, and do not give birth to live young. Monotremes are also equipped with cloacae (one hole for urination, defecation and reproduction), they are completely toothless and have electroreceptors, thanks to which they can sense weak electrical signals from afar. Scientists believe that monotremes from an ancestor living in, which preceded the split of the placental and marsupials hence their uniqueness.

Pangolins

steppe lizard

Also known as pangolins, pangolins have large, horny, diamond-shaped scales (composed of keratin, the same protein found in human hair) that overlap and cover their bodies. When threatened by predators, these creatures curl into tight balls, and if threatened, they exude a foul-smelling liquid from their anal glands. Pangolins are native to Africa and Asia, and are almost never found in the Western Hemisphere except in zoos.

artiodactyls

Mountain goat

These are placental mammals that have developed third and fourth fingers, covered with a thick horny hoof. Artiodactyls include fauna such as cows, goats, deer, sheep, antelopes, camels, llamas, and pigs, which is about 200 species worldwide. Almost all artiodactyls are herbivorous (with the exception of omnivorous pigs and peccaries); some members of the order, like cows, goats and sheep, are ruminants (mammals equipped with additional stomachs).

Primates

pygmy marmoset

It includes about 400 species and in many respects its representatives can be considered the most "advanced" mammals on the planet, especially in terms of the size of their brains. Non-human primates often form complex social units and are capable of using tools, and some species have dexterous hands and prehensile tails. There is no single feature that defines all primates as a group, but these mammals share common features such as binocular vision, hairline, five-fingered limbs, fingernails, developed cerebral hemispheres, etc.

jumpers

short-eared jumper

Jumpers are small, long-nosed, insectivorous mammals native to Africa. Currently, there are about 16 species of jumpers, which are grouped into 4 genera, such as proboscis dogs, forest jumpers, long-eared jumpers and short-eared jumpers. The classification of these small mammals has been a matter of debate; in the past, they have been presented as close relatives of mammalian ungulates, lagomorphs, insectivores, and arboreal shrews (recent molecular evidence indicates a relationship with elephants).

Bats

Spectacled flying fox

The team members are the only mammals that are capable of active flight. The order Chiroptera includes about a thousand species, divided into two main suborders: Megachiroptera(winged) and Microchiroptera(the bats).

fruit bats also known as flying foxes, have large size body relative to bats, and only eat fruit; bats are much smaller and their diets are more varied, ranging from pasture blood, insects to flower nectar. Most bats, and very few fruit bats, have the ability to echolocate - that is, they pick up high-frequency sound waves from the environment to navigate through dark caves and tunnels.

Sirens

The semi-marine mammals known as pinnipeds (including seals, sea lions, and walruses) belong to the order Carnivores (see below), but dugongs and manatees belong to their own order, Sirens. The name of this unit is associated with the sirens from Greek mythology. Apparently starving Greek sailors mistook dugongs for mermaids!

Sirens are characterized by their paddle-tailed tails, almost vestigial hind limbs, and muscular forelimbs by which they control their bodies underwater. Modern dugongs and manatees have a small body size, however, representatives of a recently extinct family sea ​​cows may have weighed up to 10 tons.

marsupials

An infraclass of mammals that, unlike placental mammals, do not carry their young in the womb, but incubate them in specialized pouches after an extremely short interval internal pregnancy. Everyone is familiar with kangaroos, koalas and wombats, but opossums are also marsupials, and for millions of years the largest marsupials on Earth lived in South America.

In Australia, marsupials have managed to displace placental mammals for most of the year, with the only exceptions being jerboas that made their way from Southeast Asia, as well as dogs, cats and livestock introduced to the continent by European settlers.

Aardvarks

Aardvark

The aardvark is the only living species in the order Aardvark. This mammal is characterized by its long snout, arched back and coarse coat, and its diet consists mainly of ants and termites, which it obtains by tearing open insect nests with its long claws.

Aardvarks live in forests and grasslands south of the Sahara, their range extends from southern Egypt to the Cape Good Hope, in the south of the continent. The closest living relatives of the aardvark are artiodactyls and (somewhat surprisingly) whales!

Tupai

indonesian tupaya

This order includes 20 species of tupai, which are native to rainforest South-East Asia. Representatives of this order are omnivores, and consume everything from insects to small animals, and flowers such as. Ironically, they have the highest brain-to-body ratio of any living mammal (including humans).

Predatory

and domestic cats), but also hyenas, civets and mongooses.

Canids include dogs, wolves, but also bears, raccoons, and a variety of other carnivores, including seals, sea ​​lions and walruses. As you may have guessed, carnivores are characterized by sharp teeth and claws; they also possess at least four toes on each foot.

proboscis

bush elephant

You may be surprised to learn that all the worlds from the order are divided into only three species (or two according to some sources): the African bush elephant, the African forest elephant and the Indian elephant.