Subclass placental representatives. The main orders of placental mammals
Lesson topic: Higher, or placental, animals: insectivorous and bats, rodents and hare-like, predatory.
The purpose of the lesson: To expand knowledge of the diversity of mammals, to show their biological characteristics, lifestyle and significance in nature and human life.
Tasks:
Educational: creating conditions for students to familiarize themselves with the features of insectivorous, bats, hare, rodent and predatory orders, to give an idea of \u200b\u200bthe individual representatives of these orders, the role of animals of the studied groups in nature and human life.
Developing:
To develop logical thinking, memory, mindfulness, the ability to generalize, compare, establish causal relationships, to single out the main thing from the entire amount of information, cognitive interest.
Educative:
Formation of a feeling of love for nature, understanding of its fragility and the need for protection.
Equipment: presentation of slides, didactic material.
Lesson type: lesson travel, learning new material.
I . Motivation and orientation stage
Hello guys!
Today we will travel to a country that is not on the map, but you are already familiar with some residents of this country, and you have to find out about the rest!
What kind of country is this, you must guess by guessing the riddle.
Once a rabbit came
At the reception of the king of animals.
Everybody is shaking, paws are shaking
Huddle near the door.
Terrible, strong, proud
The mighty king met them
He was wise, fair.
What kind of animal are you talking about? (A lion)
II . Operational and executive stage
Journey to the world of mammals.
But why suddenly among a wide variety of species, I remembered this animal?
(King of beasts)
What class of vertebrate animal does it belong to?
Around as far as the eye can see
Crown of Creation - Upper Class
Prosperous creatures
Mammals!
Indeed, the country we are going to is called the country of higher mammals or animals, where the lion is the king!
For acquaintance, I chose 5 most important groups of placental mammals (diagram on the board). You will introduce the rest of the units in subsequent lessons.
Why are they called placental?
(Placental animals - animals that have a special organ in the placenta for carrying babies during the period of fetal development).
And the theme of our lesson "Higher, or placental, animals: insectivorous and bats, rodents and hare-like, predatory(1 slide)
What do you know about higher placental mammals. About these units. (Work with the table)
Students read a textbook test, write out the biological features of the structure of the units. 1st row from 263-265 - insectivorous and bats, 2 row from 265-266 - rodents and hare-like, 3rd row from 266-267 - predatory (wolf, cat, bear, marten)
During the lesson you will get acquainted with the variety of higher placental animals, their features, their role in nature and human life, the protection of species.
Cerebral hemispheres without gyrus;
The muzzle is extended into the proboscis.
Hedgehog, mole, shrew, Russian muskrat
Bats
Adapted to flight;
Between the forelimbs, torso, hind limbs and tail stretched leather membrane;
The sternum has a keel;
Possess echolocation;
Ordinary night light, red evening light, winged
The front surface of the incisors is covered with durable enamel, so they grind off at the back than at the front, and always remain sharp;
incisors are constantly growing, there are no fangs, so there is an empty space between the incisors and molars;
molars have a flat surface;
eat plant foods;
the intestines are elongated with a well-developed cecum, where hard fiber is digested;
Mouse, vole, gopher, beaver, squirrel
Hare
In the upper jaw there are two pairs of incisors: longer ones are outside, short ones are located behind them from the inside;
eat plant foods;
the intestines are elongated with a well-developed cecum, where hard fiber is digested.
Brown hare, white hare, wild rabbit, pika
Eat animal food;
teeth are well developed, especially on top jaws - large pointed fangs and pre-radical, on lower jaw- the first radical, large and having sharp high peaks - they are called predatory teeth;
the coat is long and thick;
the stomach is simple, the intestines are short
well developed forebrain hemispheres having meanders.
Weasel, tiger, polar bear, fox
After filling out the physical education table: put the pens on the table, look at me, turn your head to the left, right, lower your hands along the body, raise, continue to work.
Insectivores are the oldest group of mammals in our country .. This is a relatively primitive group of animals.
Guys, what primitive features in the structure are characteristic of these animals? The textbook p. 263 will help us answer this question. (undifferentiated, very short, the brain is small without convolutions. apparently back in the days of the first dinosaurs).
(The teeth are small, undifferentiated, very short, the brain is small without convolutions).
In the swampy areas of Central Russia there is a small, semi-aquatic animal, a Russian desman. It is 20 cm in size, and the tail is the same length. The desman has a thick brownish-silver silver fur. It has become very rare due to habitat disturbance. It feeds on mollusks, worms, and insects.
Insectivores play an important role in nature and human life. They dig and loosen the soil, contribute to its improvement, regulate the number of insects in the forest litter, but among them there are carriers of infectious diseases.
The smallest of the insectivores is a dwarf shrew, and the largest European mole.
Perfectly guided in absolute darkness thanks to a unique echolocation system. They are able to fly 100 km. Guys, what kind of animals are you talking about?
Batwing squad.
There are many legends about these little animals.
These animals, like birds, are capable of flying.
What adaptations do bats have to fly?
To confidently fly in the darkness and darkness of caves, bats in the course of evolution have developed a complex echolocation mechanism.
What is echolocation? (we turn to the textbook p. 264)
Bats emit a series of narrowly focused ultrasonic squeaks and instantly determine their location by the reflection of sound from various objects.
Role in nature. Bats of our country feed on insects. They destroy agricultural pests, mosquitoes. In the tropics, there are vampires that feed on blood. Colonies usually form and unfortunately due to deforestation, the use of pesticides, the number of these animals is sharply reduced. Many species are listed in the Red Book of Russia.
Rodents.
This is the most numerous detachment.
Guys, do you know which animals grow teeth throughout their lives?
Valid in rodents.
2 incisors in the upper and lower jaw grow throughout life. Powerful incisors grind themselves when eating rough food and are always sharp.
Rodents are characterized by great fecundity, rapid growth, early puberty, therefore, they have a wide variety of species
Among the rodents there are forest builders - beavers.
From your own observations, name the role of rodents.
Rodents harm crops, spread infectious diseases, but there are also fur animals with valuable fur (squirrel, muskrat, nutria, chinchilla).
Among the rodents there are both the smallest - mice about 5 cm long, and very large animals - the South American capybara, or capybara, which reaches 130 cm in length. (Cl 17)
Hare. Representatives are very similar to rodents, but have a slight difference in the structure of the teeth. On page 265, find the hallmarks of rabbits and rodents. (In the upper jaw there are 2 pairs of incisors, longer on the outside, short behind them on the inside.)
We are approaching the most daring and courageous - a predatory detachment.
The main signs of the detachment (sl.23-24)
There are predatory teeth, fingers end with claws, the brain with convolutions, easy to train.
Well developed color vision. Many have valuable fur. Predators play an important role in nature, they are called orderlies. How do you understand the role of orderlies?
Predators vary in size and lifestyle.
In the squad of 7 families, in the school course we will meet with representatives of 4 families.
Wolf family(vv. 25-27)
Who is cold in winter
Walking angry hungry
Feline family(p. 28-32)
Less tiger, more cat
Over the ears of the brush are horns.
It seems meek, but do not believe
This beast is terrified in anger
Bear family(p. 33-35)
Who lives in the deaf forest
Clumsy, clubfoot?
In the summer, eating raspberries, honey
Does he suck his paw in winter?
(bear)
The Kunyi Family (Slov. 36-39)
What is this animal?
(marten is a representative of the cunyi family)
We work in pairs of replaceable staff. Option 1 - the Wolf family.
Option 2 is the Feline family, Option 3 is the Bear family, Option 4 is the Kunya family (the guys read the text on page 267).
We only met a small number of species of placental mammals, in fact, there are much more of them in wildlife. Placental play an important role in nature. Therefore, you need to take care of nature, protect animals, love them. After all, the number of many is sharply reduced; they require special attention. Such species are listed in the Red Book of Russia and our region. On a break, you can see the pages of the Red Book.
You did an excellent job and the animals are very grateful to you
III . Reflective Assessment Phase
The subject Mammals is found in Kimah OGE, complete tasks.
Select all the correct answers.
1.Backup:
a) kangaroo b) rat c) platypus d) echidna
2. Hedgehog belongs to the order:
a) bats; c) rodents
b) insectivores d) hare-like
3. Marsupials:
a) echidna b) koala c) platypus g) kangaroo
4. Bats belong to the order:
a) rodents c) bats
b) insectivorous d) predators
5. To rodents not applicable:
a) hamster b) hare c) mouse d) gopher
6. The Kunih family includes:
a) fox b) raccoon c) sable d) jackal
Intercheck: 1vg 2b 3bg 4v 5b 6v
The task of introspection.
Complete the sentences:
I learned a lot.
It will come in handy in my life.
There was something to think about in the lesson.
For all questions arising during the lesson, I received (a) answers
So our meeting has come to an end, but this is our meeting, and the meeting with mammals will last a lifetime.
Wherever you are, in the forest, steppe, on the banks of a river or the sea, you will meet mammals everywhere.
D / s P. 55, question 2,3 (in writing in a notebook)
Prepare a message for your comrades about the most amazing beast of any detachment, without naming it.
Infraclass: Eutheria, Placentalia Gill, 1872 \u003d Placental, Higher Beasts
- Systematics: Squadron: Ungulata \u003d Ungulates
- Order: Artiodactyla Owen, 1848 \u003d Artiodactyls, double-toed
- Order: Perissodactyla Owen, 1848 \u003d Oryxes
Mammals (or Beasts) - the highest class of vertebrate animals, crowning the entire system of the animal world. Today, there are several more than 4000 species of living mammals.
Mammalian biologyMammals are distributed almost throughout the Earth: they are not only on the Antarctic continent, although seals and whales are kept on its coast. In the area of \u200b\u200bthe North Pole there are polar bears, pinnipeds, cetaceans (narwhals). Mammals are also widespread in living environments. Suffice it to recall that along with the terrestrial species 
the majority of which, a number of species are more or less connected with the aquatic environment; many actively fly through the air; in addition, a significant number of animals live in the soil, where all or most of their lives pass. No class of vertebrates has given such a diversity of forms as mammals. The degree and nature of the relationship with living environments is different. Some animals live in a very diverse environment. For example, the common fox is common in forests, steppes, deserts, and in mountainous regions. Wolves live in even more diverse conditions (except for the indicated zones for the fox, wolves are also found in the tundra). Naturally, such animals do not have clearly expressed adaptations to life in any particular environment. Along with this, a specific habitat determines many features of animals. Among the inhabitants of tropical forests stand out, for example, South American sloths, arachnids, some South Asian bears, all or almost all of their life passes in the crowns of trees. Here they feed, rest and breed.
Class Mammals (Mammalia) is the highest class of vertebrate animals, crowning the entire system of the animal world. Today, there are several more than 4000 species of living mammals. The structure and appearance of mammals is diverse, which is explained by the amazing variety of their typical living environment - the surface of the trees, tree crowns, soil, water, air. Body sizes also vary greatly - from 3.8 cm with a mass of 1.5 g to 30 m and even more with a mass of about 150 tons. The most important features of the general organization of mammals are:In higher animals, or placental, the embryo develops in the uterus of the female, where the placenta is formed. Placental have a constant high body temperature (+ 36-38 ° C). The highest animals make up the vast majority of the existing mammals (about 4,500 species).
A number of insectivores combines placental mammals of a primitive structure. These animals are small in size, feed mainly on small invertebrates and insects. This explains the origin of their name. A distinctive feature of these mammals is the nose, which has the appearance of an elongated proboscis, and a thick velvet coat (mole, muskrat) or hard needles (in a hedgehog).
Insectivores are the oldest placental mammals. They are the ancestors of all modern higher animals.
Hedgehog family. It includes unusual and cute animals. The back, sides and nape of the hedgehogs are covered with hard needles (this is a modified hair). The abdomen and muzzle have a rough coat. In case of danger, the hedgehogs curl into a ball due to the action of well-developed subcutaneous muscles (these are the very muscles that raise the hair on your hands on end and form “goose bumps”). common hedgehog lives in forests, fields, gardens and even in parks of large cities. It feeds on insects, worms and small vertebrates (mice, lizards, small snakes), which are easily hunted, despite its clumsy appearance.
Many are surprised - how does a hedgehog mother give birth to such a prickly creature? It turns out that the rabies are born pink and naked, and a few hours after birth, soft needles begin to grow in them, which harden in a few days.
The mole family combines underground and aquatic animals. The common mole is widespread in our country - small, small animal covered with short velvet fur, lives in the soil (Fig. 144). Crete almost never comes to the surface of the soil, and its underdeveloped eyes hide under folds of skin. Long passages - the animal lays the galleries with strong front paws - shovels. Crete feeds on earthworms and insect larvae that are found in its underground passages.
Shrew family. Representatives of the genus externally resemble small moles, but lead a land or semi-aquatic lifestyle. In all our forests and meadows, the common shrew is common - a small animal of dark color with a muzzle - proboscis (Fig. 144).
A characteristic feature of the shrew is a dark brown enamel on the teeth. The shrew has its own time measurement during the day, she goes to bed four times and wakes up four times. During wakefulness, the animal eats insects and worms more than it weighs itself. the food in the shrew is digested very quickly, so in a few hours it is again hungry.
The Bat family (Fig. 145) unites ancient mammals that have adapted to free flight. This series includes more than 900 species of placental mammals. Bats are distinguished in a row in it. If you have to carefully examine the bat, you will make sure that the bats are not at all scary, but even funny sounds. - The bat has a fairly wide, large, dog-like nose, small wide-set eyes, a mouth as big as a smile, and big, slightly pinched ears.
The main feature of bats is the presence of these wings and the ability to prolonged flywheel.
»Bat wings are modified forelimbs. A flying membrane is stretched between the fingers, shoulders, body and hind limbs, which increases the surface of the wing. / (Remember how the surface of the bird’s wing increases.) Bats, like birds, have a keel, to which strong pectoral muscles attach, raise wings Thanks to this device, bats can fly, albeit at a low speed (only 20-30 km / h), but almost as masterly as the birds, but they can’t soar like eagles.
[Thanks to echolocation - the ability of living organisms to transmit and pick up ultrasound waves reflected from various objects that cannot be perceived by the human ear, bats are well oriented in space and prey on insects. “They emit ultrasounds through the nasal and oral openings and, using the large auricles, capture the reflections of these sounds from surrounding objects. By the nature of the reflected sound, the bat recognizes obstacles in its path, the insects that feed on, and enemies - birds of prey, determines the distance to them and even the speed of their flight.So, ears for a bat are the same as eyes for a person.
They tried to solve the mystery of bats about 200 years ago, when the Italian scientist JI. Spallanzani found that the bats are perfectly oriented in absolute darkness, and night birds - owls - are helpless under such conditions. He investigated if the ears are covered with flying wax, then in the dark he loses his ability to orientate himself, and the bat “sees” in the dark with his ears. Later this version was refuted and put forward a new one - bats tend to have some kind of unknown "tactile in the distance." And only in the XX century. Scientists have found that bats emit ultrasounds that bounce off surrounding objects and, when they come back, help bats navigate in space.
Small bats feed on mosquitoes, midges, night butterflies and even big bugs. Large bats, common in the tropics, hunt in the air, on land and in water - so that the prey is a suitable size. They feed on various insects, small birds, lizards, mouse-like rodents and even fish, which are found thanks to echolocation, capturing the slightest ripples on the surface of the water.
Interesting, but also terrible, are bloodsucker bats (they should not be confused with vampire bats, which, despite such an eerie name, do not belong to real bloodsuckers). Bloodsuckers are found in South and Central America. their upper canines and incisors have razor-sharp cutting edges. Small nocturnal animals are able to move quickly, like giant spiders, over the victim’s body. Bloodsuckers feed only on the blood of large mammals: horses, cows, goats and pigs. Sometimes they attack people who sleep. At night, the bloodsucker creeps up to the animal, makes an incision on the skin and licks the blood flowing out. The wounds then bleed for a long time and heal very slowly.
In Ukraine, more than 20 species of bats are common. All of them need special protection. The usual species of our fauna are red-headed evening-eye, night-night water-eye, common rabbit, late Lylyk (this bat more often happens in cities near human habitation). Many species of bats are rare or endangered, they include a large horseshoe, a night pond, and the evening party is huge.
The Rodent series is the largest group of mammals (Fig. 146). The ubiquitous mice and rats, alluring squirrels and dormouse, jerboa jerboas, funny hamsters and amazing porcupines - these are just a small part of rodents. The series unites about 2200 species of small and medium-sized animals, which makes up almost half of all known species of mammals.
Signs that help distinguish a rodent from other mammals are the absence of fangs and the presence of only two pairs of developed incisors that grow throughout life (Fig. 147).
The vast majority of rodents are herbivorous animals. their diet is quite diverse and depends on the season and habitat. They feed on juicy greens, fruits, seeds, root vegetables and young bark. Some rodents do not follow a plant diet; they also feed on insects and even small vertebrates. However, rodents do not hunt specifically, but eat prey, it happens by chance.
Rodents are extremely prolific. Female vole gray 3-4 times a year gives birth to 5-10 children, which become sexually mature in a month and begin to breed. So, one pair of voles per season can give rise to about 180 individuals.
European beaver is the largest in size among rodents common in our country. He deftly swims and dives. He lives in holes that he digs on the shore, or builds from the branches the so-called “beaver hut”. In summer, the beaver feeds on aquatic vegetation, and in winter - branches and tree bark.
The common squirrel lives in all our forests and even in large parks. It is adapted for climbing trees, jumping from branch to branch, has fluffy fur, long ears and a tail. The nest is arranged like a bird, high on a tree. The squirrel eats seeds, nuts, acorns, juicy fruits, berries and mushrooms, eats insects with pleasure. She is even able to behave like a predator - destroys bird nests. Gophers and groundhogs, although they are close relatives of the squirrel, are not able to climb and jump in trees. They live in large colonies in burrows, lead a daily life. They feed on grass, roots and seeds, hibernate for the winter. These animals differ significantly in character and appearance. In particular, the speckled ground squirrel is a fragile creature with a vulnerable character. He stands for a long time on his hind legs, lowering the front on his tummy, and from time to time squeals, warning of danger. He is nervous in vain. About 60 years ago, there were so many gophers on the territory of Ukraine that they damaged agriculture, and now the gopher is an endangered animal.
The well-fed and venerable marmot of the steppe (baibak) looks different - a heavy body on small paws. This animal has a calm balanced character. The little groundhog is easy to tame.
Sonya Gray is a representative of a special group of ancient rodents. In her habits and even outwardly (fluffy tail, tenacious paws), she resembles a squirrel. The animal has large eyes and sees well at night. Sonya arranges a nest of leaves in a hollow tree. Falls into hibernation for the winter.
Rodents include jerboa, living in the steppes and deserts. Jerboa has long ears, large eyes and a long tail with a tassel at the end. He is able to jump on his hind legs, like a little kangaroo.
Hamsters are not only those short-tailed pets that are often kept at home. Hamsters, common in America, cleverly climb trees. They resemble long-tailed mice living in our area. A typical representative of our fauna is an ordinary hamster.
Oddly enough, but mice are tropical animals that have moved to our lands. Most species of mice live in fields and forests. In human homes, a house mouse happens.
A mammalian species close to mice is a gray rat, which is used to the human environment, has settled on the land of the entire globe, becoming a real disaster for civilization. Rats cause significant damage to agriculture, destroying almost half of the crop in some countries. They are capable of transmitting pathogens of dangerous diseases. Once such a disease was a plague. Nowadays, there remains a danger of contracting leptospirosis if you swim in bodies of water with stagnant water, near which gray rats live.
On the territory of Ukraine there are quite unusual and little-studied animals - blind people who live in the soil, digging long galleries in it and eating roots and tubers of various plants. Blind people throw out the extra soil of underground passages in the same way as moles, but they pile up heaps of land, much larger than moles (up to 1 m in diameter). Outwardly, blind people are not like moles or any other animals: their huge incisors, with which they dig soil, come out and make a terrible impression. Most species of mole rats are listed in the Red Book.
The vast majority of mammals, including all animals living in Russia, belong to the placental subclass.
They differ in the nature of reproduction and development of the embryos that develop in the uterus. A close connection is established between the embryo and the walls of the uterus of the mother with the help of a special education - the placenta (child's place). Through the placenta and the umbilical cord, both nutrients and oxygen enter the body of the embryo from the mother's body. This allows the embryo of the placental mammal to remain in the mother’s uterus for a relatively long time and achieve more complete development than embryos of marsupial animals.
There are no placental bags. The jaws carry teeth, usually clearly divided into incisors, fangs and molars.
Zoologists divide the subclass of placental into a number of orders, of which we describe only the main ones:
· Insectivorous squad
Hedgehogs, moles, shrews belong to the order insectivores. These are small animals with a number of primitive features of the structure. Teeth are not clearly divided into groups. The hemispheres of the brain are small, with a smooth surface. Characterized by a small movable proboscis at the end of the muzzle, which animals sniff around objects.
· The squad of bats (bats)
Bats are the only group of mammals whose representatives are capable of active flight. Their wings are formed by a thin flying membrane stretched between the elongated toes of the forelimbs and hind legs, as well as between the legs and tail. Waving movements of the wings are carried out by reducing the powerful pectoral muscles, attached to the sternum, on which there is (like a bird) a longitudinal keel.
Bats are nocturnal animals hiding during the day in caves, in attics, in hollows and other shelters. In the same places they hide for the winter, which they spend in a state of deep hibernation; some winter species fly to warm countries. When flying in the dark, bats use an auditory location: they emit intermittent sounds of high frequency (not heard by the human ear) and perceive their echo reflected by various objects. This allows them to avoid collisions with obstacles in the dark and catch flying insects. Bats are very useful in killing harmful nocturnal insects (usually inaccessible to birds). In tropical countries there are large bats-winged bats (reaching a wingspan of 1.5 m), feeding on fruits.
· Predatory squad
Predators include wolves, foxes, arctic foxes, dogs, lions, tigers, leopards, lynxes, wild and domestic cats, sables, martens, ferrets, minks, otters, ermines, weasels, hyenas, bears.
Most of these animals feed on the meat of various animals, birds and fish. But some of them (for example, bears) eat both animal and vegetable feed. The teeth of predatory animals are usually adapted to grasp, kill and tear their prey. Small incisors are chisel-shaped. Behind them, very large conical fangs are issued, with which predators hold and kill their prey. Molar teeth with rows of sharp or (less often) blunt tubercles are adapted to separate pieces of meat, and not to chew food - therefore, predators usually swallow it in large pieces. One of the molars of each jaw reaches a particularly large size and carries large tubercles - these teeth are called predatory.
· Pinniped squad
covers different types of seals, walruses, fur seals, sea lions. The life of these animals is closely related to the aquatic environment, which led to many features of their organization. The body is usually a torpedo streamlined shape. The limbs are turned into flippers and serve as fins. The hair cover in most species is reduced to one degree or another. A thick layer of fat is deposited under the skin.
The pinnipeds spend most of their life in the sea (some forms live in large lakes), but they always give birth and feed their young on the shore or on ice. They feed on fish and other aquatic animals. They serve as an object of fishing, as they provide valuable lard, leather or fur skins, meat.
Squad of cetaceans
The cetacean order includes various species of whales and dolphins. The structure of marine animals bears signs of adaptation to life in the aquatic environment, which they never leave. Streamlined body. The forelimbs are flippers, the hind limbs are atrophied. At the end of the body is a horizontal caudal fin. The skin is bare, under it is a thick layer of fat. There are toothed and toothless whales.
Toothed cetaceans include dolphins and sperm whales. Their jaws carry teeth (sperm whales have teeth only on the lower jaw). They feed mainly on fish and cephalopods. Toothless whales have no teeth, but there is a special filter apparatus in the mouth from the rows of horn plates hanging from the palate (the so-called whalebone) with a fringe of fibers. Filtering water through the rows of these plates, the whales trap various small animals (mainly crustaceans) with which they feed.
Whales and dolphins give birth to cubs and feed them milk in water.
Whaling, which is now concentrated mainly in the Antarctic, provides valuable fat, meat and a number of other products.
· Rodent squad
Rodents. The most species-rich mammalian order. Rodents include squirrels, ground squirrels, groundhogs, dormouse, jerboas, beavers, hamsters, various voles, mice, rats, etc. A common feature of all rodents is a peculiar structure of teeth. In the upper and lower jaws there is only one pair of large chisel-shaped incisors with constant growth. The animals gnaw solid food with them. Fangs are missing. The molars are separated from the incisors by wide toothless gaps. The molars are adapted to grinding solid food; they have a flattened chewing surface with tubercles or enamel ridges and folds.
Among rodents, there are many plant pests - gophers, hamsters, field voles, mice, etc. But some species provide valuable fur skin and therefore serve as an object of fishing (squirrel, muskrat, beaver, etc.). A number of rodents are carriers and virus carriers of some dangerous diseases of animals and humans (plague, tularemia, etc.).
· Order rabbit-like
This includes hares and rabbits, as well as small animals - pikas. These animals are close to rodents, but differ from them in that their upper jaw carries two pairs of incisors, of which the anterior ones are large, chisel-shaped, and the posterior ones are small, columnar. Hares are a favorite prey of hunters. Rabbits are bred for meat and skins.
· Artiodactyl squad
The artiodactyl squad includes: from wild animals - various types of bulls, mountain goats and rams, antelopes, deers, camels, wild boars, hippos and other animals, and from agricultural animals - cattle, sheep, goats, pigs, reindeers, camels . All of these animals have legs with either two or four toes. The first finger is always atrophied. In those species whose extremities have four fingers, both lateral ones are usually underdeveloped and significantly less than two middle ones. The ends of the fingers are dressed in durable horn-hoof covers that protect them from damage when hitting the soil with fast running.
Cattle, sheep, goats and many wild artiodactyls belong to the group of ruminants. The digestive process of these animals is peculiar. The stomach has 4 chambers: a scar, a grid, a book and an abomasum.
· The artiodactyl squad
Horned animals include horses, zebras, donkeys, and rhinos. As in artiodactyls, the ends of the fingers of these animals are dressed in horn covers - hooves. The third (middle) finger is most developed, while the other fingers are less developed or rudimentary. Horses and donkeys bred in our country have only one middle finger on each foot.
Domestic horses are bred from an extinct wild horse - the tarpan, very similar to Przewalski's horse. Nowadays, many different breeds of horses-heavy trucks, harnesses, and riding horses have been created.
In some deserts of Central Asia, in some places preserved kulans - animals combining the signs of horses and donkeys. Domestic donkeys are bred in many southern regions of our country as draft and riding animals.
Huge rhinos inhabit the forests and savannahs of Africa and South Asia. They have three toes on their feet. Fat leather carries rare gross hair. On the nose and forehead, one or two sharp horns.
· Squad proboscis
Representatives of the proboscis squad are African and Indian elephants. These huge animals (weighing up to 5 tons) are characterized by a large trunk, five-fingered legs (each finger of which is dressed with a hoof), huge incisors of the upper jaw, turned into a pair of tusks, thick, almost bare skin. They live in tropical forests and savannahs. They feed mainly on branches of trees and bushes. Mammoths related to elephants inhabited Europe and Siberia during the ice age.
· Squad primates
Primates, the closest group of mammals to humans. They are distinguished by a strong development of the brain, especially its hemispheres, having a complex system of furrows and convolutions. On the paws, as well as on the hands of a person, the thumb is opposed to others, which makes it easier for them to grasp the branches when climbing. Fingers at the ends carry nails. Cutters 2 pairs.
Monkeys are found in tropical and subtropical countries. Usually live in packs. They feed on a variety of animal and plant foods.
Of particular interest is the group of anthropoid apes (chimpanzees, gorillas, orangutans, etc.), according to a number of signs closest to humans.
According to its anatomical structure, a person also belongs to this unit. Its similarities and differences with other mammals, in particular with monkeys, are described in the next section.
Mammals - warm-blooded terrestrial vertebrates whose body is covered with hair . The mammals class unites animals that are characterized by live births and milking of babies, complete separation of arterial and venous blood flow, highly developed ability to thermoregulate, providing constant body temperature, highly developed gray cortex of the cerebral hemispheres, which is the basis of extremely complex and perfect behavior and learning ability.Currently, the class of mammals includes more than 4.5 thousand species and is divided into three subclasses.
First beasts, or cloacal , - a group of primitive mammals that lay eggs and are common in Australia and on adjacent islands. Jaws turned into a beak, wearing a horn cover. They have cesspool, like birds and reptiles. Numerous ducts of the mammary glands open in special areas of the skin - glandular fields. Adult oviparous teeth do not, but young platypuses have teeth very similar to those of Mesozoic animals.
First beasts have hair, but body temperature (22-36 ° C) is relatively low and variable.
Marsupials (kangaroo, marsupial wolf, American possum, marsupial squirrel, etc.) unite the lower mammals, the main feature of which is a very weak development of the placenta. In this regard, the cubs are born underdeveloped after a short period of intrauterine development and continue to develop in a leathery bag on the belly, into the cavity of which the nipples open.
The third subclass is placental, or higher animals , - the largest and most highly organized group of modern mammals distributed on all continents and in the most diverse conditions. In addition to numerous terrestrial species, there are species flying, semi-aquatic, aquatic, inhabiting the thickness of the soil.
Mammals are extremely diverse in structure and size. The smallest of them (baby shrew, shrew, baby) weigh about 2 g, the largest (blue whale) - more than 120 tons.
The structure of individual organs and systems reflects the high organization of mammals in general.
The skin has a more complex structure than other vertebrates. Coat, and in aquatic species (whales, seals) - subcutaneous fat protects the body from excessive heat loss. The skin blood vessels, the diameter of which can vary widely, and sweat glands, the evaporation of the secrets of which from the surface of the skin increase heat transfer, take part in the processes of thermoregulation. Sweat glands are developed in mammals to varying degrees. They are absent in sloths, cetaceans, poorly developed in dogs and cats.
In addition to sweat, mammals have sebaceous and odorous glands (a modification of sweat or sebaceous glands). The sebaceous glands form a fat-like secret, which serves to lubricate the hair and the surface layer of the epidermis.
Excretions of these glands provide non-wetting of the coat of aquatic animals. The secret of odorous glands plays a large role in the life of mammals (along with urine and other secretions). Smelling discharge serves as a means of intraspecific communication. With their help, animals mark the boundaries of the areas occupied by them, find their cubs. They are of great importance in mating behavior. Modifications of the sweat glands are the mammary glands.
The epidermis forms numerous derivatives - in the noses, nails, claws, hooves, horns, scales. Hair modifications are bristles and needles. The structure of this or that appendage of the epidermis is directly dependent on the conditions of existence and lifestyle of animals. So, in climbing animals, the fingers have sharp bent claws. In species digging holes, claws are blunt and flattened. In large mammals that run fast, hooves develop, while in forest species (deer, elk) the hooves are wide and flat.
The muscular system of mammals is very differentiated and includes a large number of differently located muscles. A characteristic feature of the class is the presence of a domed muscle - a diaphragm that delimits the abdominal cavity from the pectoral cavity. Its role is to change the volume of the chest during breathing. Subcutaneous musculature, which sets in motion certain skin areas, receives significant development. On the face, it is represented by mimic muscles, especially developed in primates.
The skeleton of mammals consists of an axial skeleton (spine, skeleton of the head), the skeleton of free limbs and their belts. The spine is divided into cervical, thoracic, lumbar, sacral and caudal. The cervical region is characterized by two modified first vertebrae providing head mobility, which is characteristic of all amniotes in general (). The cervical vertebrae are always seven regardless of the length of the neck.
Ribs connected to the sternum are attached to the anterior thoracic vertebrae. The remaining thoracic vertebrae bear ribs not reaching the sternum. In bats and animals with well-developed front limbs for digging, the sternum carries a keel, which serves, like birds, to attach the pectoral muscles. The skull of mammals is characterized by a relatively large brain box, which is associated with the large size of the brain. The occipital bone has ~ two condyles for articulation with the first cervical vertebra. The skeleton of paired limbs retains the basic structural features of the five-fingered limb of terrestrial vertebrates. However, due to the variety of conditions of existence, the details of their structure are not the same.
For example, in fast-moving animals, the tarsus, metatarsus, wrist and metacarpus are perpendicular, and these animals rely only on their fingers (dogs). The number of fingers of the most perfect runners - hoofed animals is reduced: animals step on the equally developed fingers III and IV (artiodactyls), or on the fingers III (artiodactyls). In bats II-V, the fingers are very elongated, between them there is a leathery membrane that forms the surface of the wing. Mammals can move fast enough. The hare runs at a speed of 55-70 km / h, the lion - 50, the gazelle - 40-50 km / h, the African elephant has a speed of up to 40 km / h. The fastest running cheetah is 105-112 km / h.
The digestive system is divided into distinct sections. The digestive tract begins only in the mammalian pre-oral cavity, formed by the lips, cheeks and jaws. In a number of species (hamsters, chipmunks, monkeys) this cavity forms large cheek pouches. Lips are used for sucking milk by babies, as well as grabbing food by adult animals. Lips have no single pass, cetaceans. Behind the jaws is an oral cavity in which food is subjected to grinding and chemical attack. Mammals have four pairs of salivary glands, the enzyme of which - ptyalin - decomposes carbohydrates. The development of salivary glands depends on the nature of nutrition. In cetaceans, they are reduced, in ruminants, on the contrary, they are very developed. For example, a cow releases about 56 liters of saliva per day.
The saliva of some shrews (a detachment of insectivores) is poisonous, reflecting the phylogenetic relationship of primitive mammals with reptiles. One of the most important signs of mammals, which appeared even in their ancestors in the Triassic, is the differentiation of teeth into incisors, fangs, anterior and radical. The teeth sit in the cells of the jawbones, the number of teeth, their shape and function are different for different groups of animals, but it is important that their differentiation indicates a high evolutionary plasticity of mammals and the possibility of their adaptation to a wide variety of foods. From the mouth through the esophagus, food enters the stomach. The stomach is isolated from other parts of the digestive tract and is equipped with numerous glands. Its internal structure in different species is associated with the nature of food. If the food is not chewed or presented with coarse plant foods, the stomach becomes multi-chamber (cetaceans, ruminants, sirens).
The intestines are divided into thick, thin and straight. The intestines are longer in herbivores than in carnivores. In species that eat coarse plant food, a long cecum departs from the border of the thin and thick sections, ending in some animals (for example, hares) with a vermiform appendix. The digestive glands (liver, pancreas), whose ducts flow into the anterior small intestine, are well developed.
The respiratory organs of mammals are represented by the lungs. Unlike reptile lungs and birds, in which the lung cavity is divided into numerous chambers by chambers, in mammals there are clusters of thin-walled vesicles - alveoli - located on the terminal branches of the bronchi - bronchioles. The walls of the alveoli are braided by capillaries. The number of alveoli depends on the mobility of the animals. Inactive sloths, there are about 6 million, in predatory ones, from 300 to 500 million. Oxygen consumption depends on the size of the animal (in large animals, the metabolic rate is lower than in small ones). So, a shrew with a body weight of 3.5 g consumes 7-10 ml 02 per 1 g of body weight for 1 h; a hare weighing 1600 g - 0.96 ml, a seal weighing 26 kg - 0.22-0.34 ml, a camel weighing 170-330 kg - 0.03-0.04 ml 02. In the same way, the number of respiratory movements depends on the size of the animals. minute: in a horse it is 8-16, in a rat - 100-150, in a mouse - about 200
Respiratory movements (ventilation of the lungs) are essential for heat regulation, especially in species with poorly developed sweat glands. In them, air cooling during its heating is largely achieved by increasing the evaporation of water, the vapor of which is removed together with the exhaled air. For example, in a dog, when the temperature of the environment rises, the quantity: water evaporated by the lungs can reach 200 cm3 / h. In aquatic mammals, conducting under water for a long time, the lungs are characterized by strong development of muscle tissue.
The circulatory system, as in birds, is characterized by a complete separation of arterial and venous blood flow, due to which the most oxidized (arterial) blood is distributed throughout the body. The heart is four-chambered, one (left) aortic arch leaves from the left ventricle. Passing in the tissues through the capillaries, the blood gives off O2, is saturated with CO, is collected in the veins and enters the right atrium. From the right atrium, venous blood enters the right ventricle, from where it goes to the pulmonary trunk during systole. The pulmonary trunk soon divides into two pulmonary arteries - the right and left, carrying blood to the lungs. From the lungs, oxidized blood flows through the pulmonary veins into the left atrium.
The relative size of the heart depends on the degree of motor activity of animals. So, in a domestic rabbit, the size of the heart is three times smaller than in a wild hare. The same pattern is revealed when comparing this indicator in a room and a beagle dog. The heart rate decreases as the weight of the animals increases (and, accordingly, the metabolic rate decreases). If in a mouse the number of heart contractions in 1 min is 600, then in a sobgka - 120, in a bull - 40-45.
The total amount of blood in mammals is greater than in lower-level vertebral groups, more importantly, mammals have significantly more red blood cells per unit volume and more oxygen capacity of blood.
The distribution of maximally oxygenated blood throughout the body of mammals and intense blood flow created the prerequisites for a constantly high metabolic rate and maintaining a constant body temperature (warm-bloodedness).
The anatomical basis of warm-bloodedness, as in birds, was the loss of one of the two aortic arches and the development of a complete septum between the ventricles.
The excretory system is represented by paired kidneys and ureters leaving them, which flow into the bladder. Urine is excreted from the bladder through the urethra. The main end product of protein metabolism in mammals is not uric acid, as in birds and reptiles, but urea. This is due to the fact that mammals evolved from reptiles that have not lost many of the features of amphibians, and in connection with the development of the placenta. Through the placenta, the embryo removes toxic products of protein metabolism. The embryos of egg-laying animals, whose metabolic products accumulate in the egg, are deprived of this possibility.
Mammals' water consumption depends on their ecology. Many species of predators and ungulates regularly go to a watering place. Ungulates in search of water can travel very long distances. There are mammals whose water needs are met by the succulent food they eat. A number of desert species (mainly rodents) do not drink at all, although they feed on dry food. The source of water supply is their metabolic water, formed in the process of metabolism Do not drink water and aquatic mammals.
Mammals are dioecious animals. Fertilization is always internal. Embryos develop in the cavity of a special department of the female genital tract - the uterus.
Embryos are fed with the help of the placenta, which is a specific formation for higher mammals that occurs as a result of the fusion of two germinal membranes - allantois (in the cavity of which metabolic products of the oviparous are secreted) and serosa. In the place where these two membranes grow together, a spongy body is formed - the chorion, which forms the villi that penetrate the uterine epithelium. The blood vessels of children and maternal organisms are intertwined, as a result of which gas exchange, nutrition and removal of decay products are provided in the body of the embryo. In different species, pregnancy varies greatly in duration. This is partly due to the size of the animals, but the conditions of existence are of primary importance.
Short pregnancy is observed in animals that give birth to cubs in places protected from adverse climatic conditions and predators (in nests, burrows, on trees, etc.). In these cases, newborns are helpless, naked, blind. The period of embryonic development in animals that give birth to cubs on the surface of the earth and in which they are forced to follow their mother soon after birth is much longer. These are ungulates (in deer, the duration of pregnancy is 8–9 months, in horses, donkeys, 10–11). For example, compare two close views. Rabbits live in holes where they give birth to blind and helpless cubs after a 30-day pregnancy. Hares do not suit nests and give birth to pups sighted, covered with wool and able to run in the first days of life after 49-51 days of pregnancy. Long pregnancy and large sizes of cubs, allowing them to lead an independent lifestyle, are characteristic of pinnipeds and whales. After the completion of milk feeding, the relationship between parents and offspring persists for quite some time: in wolves - up to one year, in tigers - up to 2-3 years. This provides the opportunity for learning - the transfer of individual experience of parents to offspring.
Mammals are considered the highest class of the animal world, not only due to the complexity and perfection of the structure of their body, but also due to the richness and diversity of the nervous system. Mammals are capable of individual training through the formation of complex conditioned reflexes, the transfer of accumulated experience to offspring, behavior changes depending on changes in environmental conditions, interaction with family members, herds or flocks, and strict regulation of relationships within these social entities. All these features are due to the strong development of the evolutionarily young part of the brain - the cerebral cortex. The cerebral cortex becomes the highest integrating link of the central nervous system, processing information coming from outside and coordinating both the activity of the body’s internal systems and arbitrary behavioral acts.
An indicator of the development of the forebrain hemispheres is the ratio of its mass to the mass of the entire brain in mammals of different systematic groups. In primitive hedgehogs (detachment of insectivores), it is 48%, in wolves - 70, in dolphins - 75, in humans - 78%. In lower mammals (insectivorous), the cerebral cortex is smooth, and as the level of organization increases, the cortex forms an increasing number of folds - convolutions. The folding of the cortex reflects both an increase in its surface and an increase in the number of neurons in the gray matter. In functional terms, the cortex is divided into a number of zones that control certain functions (motor, visual, auditory, etc.). Functional zones of the cortex are interconnected by pathways. It should also be noted the large size of the cerebellum and its differentiation into several departments, which is associated with the very complex nature of the movement in animals.
Among the sense organs in mammals, the olfactory organs are very strongly developed, which play a huge role in their life. With their help, animals identify enemies, look for food, members of their family and offspring. Representatives of many species smell for several hundred meters and find food objects that are underground. Only fully aquatic mammals (whales) are practically free of smell.
In the vast majority of cases, the hearing organ is also very well developed. It consists of two new departments: the external auditory meatus and the auricle (absent in aquatic and underground animals). The auricle significantly enhances the subtlety of hearing, especially in nocturnal animals and forest ungulates. Predators have good hearing. In the cavity of the middle ear in mammals there is not one auditory ossicle, as in amphibians, reptiles, birds, but three: a malleus, an anvil, and a stapes. The stirrup transmits sound vibrations from the anvil to the inner ear. In the composition of the inner ear, the organ of Corti is of great importance - the system of the thinnest fibers stretched in the cochlear canal (see 170). When perceiving sound, these fibers resonate, which ensures a delicate hearing in animals.
A number of animals has the ability to sound location (echolocation). These include dolphins, seals, bats. Dolphins make sounds with a frequency of 120-200 kHz and are able to locate schools of fish from a distance of 3 km. Less important in the life of mammals are the organs of vision. By visual acuity they are inferior to birds. Nocturnal animals and inhabitants of open landscapes (antelopes) have great severity and large eye sizes. In species living in the thickness of the soil, the eyes are reduced, sometimes they are tightened by the skinny membrane (mole rats, moles). Color vision is relatively poorly developed.
The class of mammals as a whole is characterized by wider and more perfect adaptability to different living conditions. Only this class has populated all habitats - terrestrial, air, oceans and the thickness of the soil.
In the process of adaptation to different habitats, mammals were divided into the following ecological groups:
I. Ground animals - the most extensive group of mammals that populated almost all of the land (with the exception of Antarctica). Among them can be distinguished animals that inhabit the forest and thickets of shrubs, and animals - inhabitants of open spaces. The first include species that spend most of their life on trees and arrange nests there (squirrels, some martens, sloths, many monkeys, etc.). Others lead a semi-woody - semi-terrestrial way of life and only partially extract food from trees. For example, sable finds most of the food on the ground (mouse-like rodents, pine nuts and berries), but also catches birds and squirrels. Many species use the forest mainly as a shelter, forage on the ground (brown bears, moose, deer, wolverines).
Inhabitants of open spaces (ungulates, jerboas, gophers) live in the absence of natural shelters and an abundance of plant food. This also includes many insectivores, predators, adapted to life in the steppes and deserts
II. Underground mammals are a small group of specialized species that spend all their life or a significant part of their life in soil. These include moles, mole rats, marsupial moles, etc. They make passages in the ground with their front paws or strongly developed incisors. They feed on insects, their larvae, and earthworms.
III. Water animals. In this ecological group, there are a number of transitions from terrestrial species to completely aquatic. For example, mink makes burrows on land - along the banks of fresh water, and feeds both in water and on land (fish, amphibians, water rat). The otter spends more time in water; its diet consists mainly of fish. She already has adaptations to an aquatic lifestyle - shortened limbs, a membrane between her fingers, reduction of the auricle. Seals are even more associated with water, which outside the water only mate and give birth to cubs. Finally, cetaceans belong to completely aquatic.
IV. Flying animals include bats, or bats.
Mammals have developed a variety of adaptations to survive the adverse conditions caused by the changing seasons of the year. These include migration, hibernation, and food storage. Mass seasonal migrations to places with abundant food are characteristic of reindeer, white hares, Arctic foxes (from the tundra to the forest-tundra and forest zone). Together with deer, wolves and wolverines migrate. In the fall, many bats fly to warmer climes.
Winter hibernation is also common among mammals - a state of reduced vital activity at a time when food becomes inaccessible. Hibernation can be of different intensities - from the surface (winter sleep), which is characteristic of bears, raccoons, badgers, to deep, characterized by numbness, lowering body temperature and a decrease in respiratory rate (hedgehogs, ground squirrels, jerboas, etc.).
Stocking food for the winter is typical for rodents. Forest mice, field voles, gerbils, beavers, squirrels store cereal grains, dry grass, acorns, tree seeds, etc.
The economic importance of mammals is extremely high. Wild species served as the source of numerous domestic breeds of mammals that satisfy many human needs (domestic dog, sheep, horses, cattle, camels, pigs and many others). The process of domestication of wild species continues in our time. Sables, minks, arctic foxes, foxes, and nutria are bred on farms. The listed species are at different stages of domestication. Great successes have been achieved in breeding silver-black foxes.
In addition, 150 species of domestic fauna can serve as objects of hunting in order to obtain meat or furs. For the sake of furs, about 50 species of wild animals (squirrel, sable, arctic fox, muskrat, hares, etc.) are hunted. Ungulates annually shoot in the amount of 500-600 thousand heads (moose, roe deer, reindeer, saigas, etc.). Acclimatization of animals is widely used to replenish stocks of valuable species. Muskrat, striped raccoon, American mink, silver-black fox, and musk ox were brought from North America. Domestic species are also being resettled in a territory suitable for natural conditions. For example, the Ussuri raccoon dog, which lived only in the Primorsky Territory, has now become common in the European part of the USSR. The number of sable and beaver has been restored. Rare and endangered species are listed in the Red Book and taken under protection. The preservation of our fauna is facilitated by the creation of a wide network of reserves, where work is carried out not only to protect certain species, but also to acclimatize new ones.
Mammals were separated from primitive non-specialized Paleozoic reptiles, which retained many more features of amphibians. Such signs should include, for example, moist skin, rich in glands, and the ability to skin respiration (albeit in negligible amounts). In the process of evolution, mammals formed a number of large aromorphoses, which increased the activity of their life activity, decreased their dependence on environmental changes and provided favorable conditions for the development of offspring: live birth, milk feeding of young cubs, developed cerebral cortex, which made possible adaptive behavior, formation of a four-chamber heart and loss one of two aortic arches, differentiated teeth. A branch was separated from primitive mammals in the Triassic, which gave rise to the modern subclass of primitives, or cloacal. Much later, in the Jurassic - Cretaceous periods, marsupial placental mammals appeared. Marsupials were quickly replaced by placental and preserved in a small number only in Australia and South America. The biological heyday of mammals came only in the Cenozoic era after the extinction of large reptiles.
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