Higher placental mammals. Placental animals. Mammals in the Jurassic
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Placental mammals are divided into 16 orders. These include Insectivores, Chiropterans, Rodents, Lagomorphs, Carnivores, Pinnipeds, Cuiformes, Ungulates, Proboscideans, Primates.[...]
The class of mammals is divided into three subclasses: oviparous, marsupials and placentals.[...]
Insectivorous mammals, which include moles, shrews, hedgehogs, etc., are considered the most primitive among placentals (Fig. 87). These are quite small animals. The number of teeth they have is from 26 to 44, the teeth are undifferentiated.[...]
The origin of mammals is usually explained by their emergence from therapsids (ancient Paleozoic reptiles) in the Late Triassic. Many zoologists believe that mammals have a polyphyletic genesis, that is, each subclass of mammals has a separate therapsid ancestor. Possessing a highly developed nervous system and other properties, mammals stood out from vertebrates as a class that conquered land. Placentals flourished in the Paleocene (55-65 million years ago). Since the Tertiary period, they are the predominant (thriving) form of life on Earth (Fig. 38).[...]
Primates are a group of placental mammals (monkeys, humans).[...]
This is exactly how many mammals hibernate: directly in response to the “deterioration” of living conditions and, moreover, after the obligatory preparatory phase. During hibernation, they acquire “stability” (by conserving energy associated with a decrease in body temperature), and during hibernation itself they regularly “stick out” and “look closely” at what is happening outside their shelters; in the end, as soon as the adversity has passed, the animals interrupt their hibernation. In mammals, particularly striking examples of reactive hibernation can be found among marsupials: when the mother’s body lacks certain resources, some marsupials are able to delay the development of the fetus for many months. Most placental mammals lack this ability.[...] Fruits and large predators
The species Homo sapiens belongs to the animal kingdom, the phylum of chordates, the subphylum of vertebrates, the class of mammals, the subclass of placentals, the order of primates, the family of hominids, and the genus of humans. (Homo), in which only one species (Homo sapiens) has survived to our time.[...]
So, for example, the ecology of animals, in accordance with their zoological classes, should be divided into the ecology of mammals, birds, amphibians, fish, insects, etc. In turn, the ecology of mammals, in accordance with their subclasses, can be classified into the ecology of oviparous (primal animals), marsupials, placental (higher animals). The ecology of placentals, in accordance with their orders, is divided into the ecology of primates, carnivores, rodents, insectivores, etc. In the ecology of primates, by analogy with their suborders, lower and higher primates should be distinguished. And finally, in the ecology of great apes one can isolate the ecology of man. It is not difficult to continue the division further, but the main thing is to comply with the division rules listed earlier.[...]
In the Tertiary period of this era, the Paleocene, Eocene, Oligocene, Miocene and Pliocene eras are distinguished. In the Paleocene, primitive placental mammals already existed. In the Paleocene and Eocene, the first carnivorous predators and the most ancient ungulates arose. In the Eocene and Oligocene, the first predators were replaced by forms that gave rise to modern cats, dogs, bears and weasels, as well as seals and walruses. As for ungulates (horses, camels and elephants), their evolution went towards an increase in body size and a change in the number of fingers. During evolution, ungulates diverged into a group with an even number of fingers (cows, sheep, camels, deer, giraffes, pigs and hippos) and a group with an odd number of fingers (horses, zebras, tapirs, rhinoceroses). In the Eocene, cetacean forms existed, giving rise to whales and dolphins. In the Oligocene, the ancestral forms of apes and humans were also widespread.[...]
In the Tertiary period, a warm, uniform climate was established. Forests, subtropical and tropical, are widespread. Placental mammals develop and replace marsupials from almost all continents. The most primitive were insectivorous mammals, from which the first carnivores and primates originated. Ancient carnivores gave rise to ungulates. Some mammals began to conquer the sea - pinnipeds and cetaceans appeared. By the end of the Tertiary period, all modern groups of mammals also developed intensively, especially those associated with flowering plants. Ecosystems began to develop. modern structure, they formed food connections between different classes and types of organisms.[...]
Man is a biosocial being and at the same time a representative biological species“Homo sapiens” (Homo sapiens), belonging to the kingdom of animals, the phylum of chordates, the class of mammals, the subclass of placentals, the order of primates, the family of hominids. Other families included in the order of primates are pongids - large apes (orangutans, chimpanzees, gorillas) and chilobatids - small apes (gibbons).[...]
Seventy million years ago, the mysterious and rapid extinction of entire clans of reptiles occurred. Then all the dinosaurs died (for reasons more likely genetic than external). Began fast development mammals. New forms of life arose everywhere on the planet. This era of the flourishing of new life is called the tertiary period Cenozoic era. In addition to oviparous and marsupial animals, animals also appeared higher order- placental. During pregnancy, the females of these animals form a special organ in the uterus - the placenta - which provides a reliable transmission system, so to speak, between the fetus and the mother bearing it. Through the placenta, the fetus receives the oxygen and nutrition necessary for breathing from the mother’s blood and removes waste products.[...]
To ensure the connection of the embryo with the environment, it develops so-called provisional organs, which exist temporarily. Depending on the type of eggs, the provisional organs are different structures. In fish, reptiles and birds, the provisional organ is the yolk sac. In mammals, the yolk sac is formed at the beginning of embryogenesis, but does not develop. Later it is reduced. During evolution, reptiles, birds and mammals developed embryonic membranes that provide protection and nutrition to embryos (Fig. 91). In mammals, including humans, these embryonic membranes become sheets of tissue developing from the body of the embryo. There are three such membranes - amnion, chorion and allantois. The outer membrane of the embryo is called the chorion. It grows into the uterus. The place of greatest growth into the uterus is called the placenta. The embryo is connected to the placenta through the umbilical cord or umbilical cord, which contains blood vessels that provide placental blood circulation. The amnion develops from the inner layer, and the allantois develops between the amnion and chorion. The space between the embryo and the amnion, called the amniotic cavity, contains fluid (amniotic fluid). This fluid contains the embryo and then the fetus until birth. Fetal metabolism is ensured through the placenta.[...]
The Cretaceous period is named due to the abundance of chalk in the marine sediments of that time, which were formed from the shells of protozoan animals. The accumulation of these deposits, consisting mainly of calcium carbonate, has led to a decrease in carbon dioxide in the atmosphere. During this period, they spread rapidly flowering plants, displacing gymnosperms. Some forms: poplars, willows, oaks, palms, eucalyptus, have survived to this day. Dinosaurs Cretaceous period differ from their predecessors. Some of them began to move on hind legs. Giant forms were still encountered. Bird development continued. By the end of the Cretaceous period, placental mammals appeared. At the end of this period, a process of intensive mountain building begins, the Alps, Andes, Himalayas, and the Caucasus rise. The climate became sharply continental and colder. This led to the extinction of all large forms of reptiles. Most of the surviving reptiles (lizards, snakes) were small in size, only in equatorial belt Quite large crocodiles have been preserved. In conditions of general cooling, warm-blooded animals - birds and mammals - gained an advantage.[...]
Endemics (from Greek - local) are plants and animals with an extremely narrow range and limited in their distribution to a particular region or country. Islands and mountainous countries are characterized by the highest degree of endemism. So, flora o. Madagascar has about 70% endemic species, Hawaiian species - 82-90%, etc. In the flora of the Caucasus there are 26% endemic species, in the flora of mountainous regions Central Asia- up to 30%, etc. The flora and fauna of Australia is especially rich in endemics, and almost all types of eucalyptus (more than 450 species) are endemic. Among endemic animals, the most interesting are marsupial bear(koala), kangaroo, marsupial wolf, possum, echidna, platypus, etc. In Australia, only two representatives - the echidna and the platypus - are oviparous. Only recently has it been possible to obtain interesting data on the platypus (Griffiths, 1988). The platypus, despite its antiquity and the combination of characteristics of reptiles and mammals, is well adapted to life in water and on land. It is most active at night, when it feeds on small crustaceans, mollusks and insect larvae. Its lifespan (ontogenesis) reaches 12 years, and it successfully reproduces into old age. Its beak contains mechano- and electroreceptors that help it find food even in muddy water. The platypus is able to regulate its body temperature (about 32 °C) better than many placental mammals. It inhabits freshwater bodies of eastern Australia and is currently strictly protected.
Placentals are common in all parts of the world, with the exception of Australia. Placentals include all domestic mammals. Man evolved from the highest group of placentals - monkeys. There are 17-18 modern units in the infra class. In higher mammals, compared to the two previously considered groups - cloacal and marsupials - the entire organization has become more complex. It was in placental animals that the nervous system reached its highest development, especially the forebrain cortex and the associated high ability to adapt to changing conditions external environment and the rudiments of rational nervous activity. The same should be said about the locomotion system, the respiratory, circulatory, digestive and other systems. The body temperature of placentals is significantly higher than that of cloacals and marsupials. It is maintained, as a rule, at the same level, which indicates a high metabolic rate and complex thermoregulation. The most advanced form of viviparity characteristic of placentals provides them with embryonic development in the most favorable conditions. Caring for offspring (feeding with milk, protection from enemies, etc.) is better developed in higher mammals than in any other animal. The ancestors of placental mammals were the so-called pantotheriums - small animals with three tuberculate teeth that existed in the Triassic and Jurassic period. The first placental mammals appeared at the end or perhaps in the middle of the Cretaceous period. These were primitive insectivorous animals. From them, at the beginning of the Tertiary period, various orders of the subclass under consideration arose, which quickly evolved throughout the entire named period in different directions, mastering various habitats. During evolution, some of the emerging groups of mammals died out and were replaced by new ones. Below are brief characteristics most modern orders of placental mammals.
Order insectivores (insectivora)
This order includes the lowest of modern placental mammals (moles, hedgehogs, shrews, muskrats, etc.). These are small or small animals with a characteristic elongated proboscis. The forebrain is small, with developed olfactory lobes, has no convolutions, its hemispheres do not cover the cerebellum, and in some even the midbrain is visible. Accordingly, the skull is small. The teeth are poorly differentiated. Many feed on insects, but a number of species can attack small vertebrates. Some species are of commercial importance. A number of species are beneficial by destroying harmful insects. They can also cause harm (for example, a mole eats many useful animals such as earthworms). The number of species is about 370.
The subclass of placentals unites most modern species of mammals, which are widely distributed throughout to the globe and have adapted to living in a wide variety of conditions. Basic distinctive feature these animals is the presence of a placenta, through which nutrients and oxygen enter the fetus's body from the mother's body. It is formed at the site of the introduction of numerous outgrowths (villi) on the outer surface of the embryo into the mucous membrane of the uterus, where a complex network of capillaries-villi is located in close proximity to the blood vessels of the uterus. Thanks to this arrangement, nutrients and oxygen from the mother’s body osmotically enter the vessels of the umbilical cord and then into the body of the fetus, and waste products are removed from it in the same way. The placenta allows the embryo to remain in the female's uterus for a relatively long time. In this regard, placentals give birth to babies that are able to independently suck milk from the mother’s nipples.
Among the other most important typical features of placentals, it is necessary to note the strong development of the forebrain, the hemispheres of which are connected by the corpus callosum, as well as the presence of an always unpaired vagina. Most species are characterized by deciduous and permanent generation of teeth (except for true molars).
Order Insectivores
The order of insectivores includes small and small placentals. In most of them, the anterior section of the muzzle is elongated into a movable proboscis, the body is covered with hair, and in some, with bristles or needles. Many species have developed scent glands. Their internal organization is relatively primitive: the braincase is quite small, the cerebral hemispheres are small and lack convolutions, the teeth are poorly differentiated, and the fangs rarely have a typical shape and size. Insectivores are considered the most ancient of the placentals.
Insectivores are widespread throughout the globe, although they are absent from Australia and much of South America.
Representative: common hedgehog
Muskrat small animal with long tail, which is laterally compressed and covered with large horny scales. There are swimming membranes between the fingers. The fur is very thick and silky. The muskrat leads a semi-aquatic lifestyle. At the beginning of the twentieth century, the muskrat was almost completely exterminated due to its valuable fur and musk glands, and currently this animal is under protection.
Moles- small animals adapted to an underground lifestyle. Their body is ridged, their head is cone-shaped, their muzzle is elongated into a proboscis, they have no ears, their forelimbs are short, but their claws are large, their fur is short, soft, and velvety. The olfactory organs are well developed, and the eyes are rudimentary. They shed difficultly, 3 times a year.
Representatives: common mole, Siberian mole.
Shrews- small and very small animals, externally similar to mice, from which they differ in their muzzle elongated into a proboscis. Their tail is quite long and their limbs are short.
Representatives: baby shrew, little shrew (the smallest mammals). The body is about 4 cm, weight is 1.5-2.5 g. During the day they eat 3-4.5 times their weight in food. They can fast no more than 5-6 hours a day.
Representatives: tiny shrew, small shrew, common shrew, water shrew.
Order Chiroptera
Small and medium-sized mammals adapted for movement in the air are combined. Their wings are made up of leathery membranes stretched between long fingers forelimbs, sides of the body, hind limbs and tail. Only the first finger of the forelimbs is free and does not participate in the formation of the wing. The sternum, like that of birds, has a keel to which the pectoral muscles are attached, which move the wings.
Chiropterans are active at dusk and at night. On the ground they are usually helpless, but in the air they are fast and agile. Vision is poorly developed, but most people have exceptionally fine hearing. The range is huge from 12 to 190 thousand Hz (a person perceives sounds from 40 to 20 thousand Hz). They navigate in space using sound location. Before the flight, ultrasounds are emitted with a frequency of 30-70 thousand Hz. Ultrasounds reflected from obstacles are perceived by the hearing organs, which allows the animal to recognize the situation in front of it and catch flying insects. They feed on a variety of foods and can even drink the blood of vertebrates. Many people can eat an amount of food equal to their own body weight per day.
The bats
– small, have sharp teeth and relatively large ears. They live in colonies or alone. Active at dusk. Developed sound location.
Blood-eating bats have a pain-relieving substance in their saliva, as well as a substance that prevents blood clotting.
In winter, they hibernate (anabiosis) or fly to the southern regions, where they accumulate in huge quantities.
Representatives: leather bats, bats, noctules, longwings, eared bats.
Fruit bats– small and medium-sized bats. Fruit bats have a keen sense of smell, acute vision, and are almost incapable of sound signaling.
Representatives: flying dog, or kalong.
Squad of rodents
Includes small and medium-sized mammals that consume mainly plant food. Their appearance is varied, but the dental system of all species is adapted to gnawing and chewing solid plant foods.
In the upper and lower jaws sits one pair of large chisel-shaped, rootless and constantly growing incisors. The front wall of the incisors is covered with enamel and is strong, while the back wall is devoid of enamel and is soft. Due to uneven grinding, the tips of the incisors are always sharp. They are partially exposed, since the upper lip is often deeply split. Molars have a wide chewing surface on which there are tubercles. There are no fangs, so between the incisors and molars there is a wide toothless gap - a diastema. Due to rough nutrition plant foods the intestinal tract is long. All species have a cecum, which is a kind of “fermentation vat.” Rodents are distinguished by early puberty and numerous offspring. There are terrestrial, underground, arboreal and semi-aquatic forms.
Squirrel- live in hollows in trees. It does not hibernate during the winter. It feeds more often on coniferous seeds, less often on berries and mushrooms.
Chipmunks– have a striped color and a relatively fluffy tail. They lead a terrestrial lifestyle, living in burrows. They hibernate for the winter, but make reserves in the fall.
Gophers And marmots live on earth. Distributed in steppe and mountainous regions. They live in burrows, feed on grass and seeds, and usually live in colonies. They can carry dangerous diseases (plague, tularemia).
Representatives: small gopher, speckled gopher, yellow gopher, bobak.
Beavers– was almost universally exterminated in the last century, but currently its numbers have increased. Beavers live in colonies along forest streams. Their homes are huts and burrows made from branches. In places of settlement, beavers build dams that raise the water level in the river.
Porcupines- the largest animals among rodents. Length 70-90 cm, and weight up to 30 kg. They are active mainly at night. During the day they hide in a shelter.
Mouse- the largest group of rodents. Most of them are small animals. They live in burrows, feed on plant foods and sometimes insects. They are distinguished by early puberty and very high fertility.
Representatives: house mouse, harvest mouse, wood mouse, gray rat, or pasyuk.
Muskrat- a large rodent with valuable fur, its homeland - North America. Leads a semi-aquatic lifestyle, lives in thickets of reservoirs, where it settles in huts and burrows. Feeds on aquatic vegetation. It multiplies very quickly. They become sexually mature at less than a year old. One of the most important fur-bearing animals.
Other representatives mouse: dormouse, jerboa, mole rat, nutria, chinchilla, Guinea pigs (domesticated forms).
Order Lagomorpha
The order unites mammals, small and medium in size, similar to rodents. The differences between them are manifested in the structure of the teeth and stomach. There are 4 incisors in the upper jaw, a pair of small ones are placed behind a pair of large ones. Their stomach resembles the stomach of ruminants, and the digestion process proceeds approximately the same as in sheep or cows. The squad includes pikas And hares.
Hares have elongated hind legs, long ears and a short tail. Very similar to rabbits. Active all year round. They rest and breed in bushes or dense grass. No special burrows are built. They escape from enemies in several ways: they lie motionless in place and, only as a last resort, run away. The speed reaches up to 50 km/h. While running they are cunning and confuse their tracks. They can also defend themselves - they fall on their backs and fight back with their strong hind legs. What helps the hares escape is their weak skin and fragile fur, which often remain in the predator’s teeth. Bunnies are born sighted and grow quickly.
Representatives: white hare, brown hare, Manchurian hare, sand hare.
Wild rabbit It has ears and legs that are noticeably shorter than those of hares. They live in colonies, dig deep holes, where they give birth to completely helpless rabbits.
pikas, or hay stands- small lagomorphs with short ears, tail and paws, often emit loud squeaks and whistles. They usually live in colonies.
Representatives: Daurian pika, northern pika
Squad Predatory
Carnivorous mammals very diverse in both appearance, and in size. What unites them is the structure of the dental system: the incisors are small, but there are large canines and carnassial teeth (strong, premolar with a sharp cutting edge). The molars are tuberculate, with developed cutting apices. The fingers have retractable or non-retractable claws, powerful development of the forebrain and the presence of convolutions on the cortex cerebral hemispheres. Most species feed on animal food, some are omnivorous or predominantly
herbivorous.
Family wolf- medium-sized animals with a sharp muzzle and ears, long thin legs bearing non-retractable claws, more or less long bushy tail. The carnassial teeth are well developed. They feed mainly on animal food and usually pursue prey for a long time.
Representatives: wolf, common fox, blue fox, raccoon dog, jackal.
Bearish- large predatory plantigrade mammals with a short tail and large non-retractable claws. Weighing up to 1000 kg, length up to 3 m.
Representatives: brown bear, polar bear, black bear
Musteluns– animals of small and medium size, have an elongated body and short limbs with non-retractable claws. The odorous glands located at the anus are highly developed.
Representatives: sable, pine marten, mink, river otter, ermine, weasel, black polecat, steppe polecat. Some of them are bred on fur farms, as they are valuable fur-bearing animals.
Family feline– predators of medium and large size, with long limbs, usually armed with retractable claws. The coloring is usually spotted or striped. The carnassial teeth are well developed.
Representatives: tiger, leopard, snow leopard, cheetah, lynx, forest cat, steppe cat, Far Eastern cat, jungle cat. Some species are protected.
Order Pinnipeds
The order Pinnipeds unites mammals with an elongated, spindle-shaped body, shortened limbs modified into flippers, and a short mobile neck.
The hair is sparse, short and coarse. Subcutaneous fat deposits, on the contrary, are very developed. There is usually no external auricle, but hearing is good. Some species navigate in space using echolocation. Vision is weak, but the sense of smell, on the contrary, is good. Dental system basically the same as that of predators. Distributed mainly in polar and temperate latitudes. Keep in coastal zone, but some go to the open sea. Most spend their lives in water. Where they feed and rest. For mating and childbirth and molting, they go out onto the ice or onto land. Pinnipeds are considered a group close to predators that switched to an aquatic lifestyle.
Walrus- up to 4 m long, weight up to 1 ton. The body is covered with thick folded skin. The tail is very short. The canines of the upper jaws, like massive tusks, are directed vertically downwards. The rear flippers can be folded forward and participate in movement on land. It lives in coastal areas of the seas, staying in groups (sometimes up to 100 animals). The main food is shellfish. Extracted using fangs.
Eared seals have small eared shells. U real seals there are no auricles. To molt, mate, and give birth to cubs, they most often go out onto the ice, where they form numerous “rookeries.” The main food is fish.
Representatives: Caspian seal, Baikal seal, seal, crested cat, sea hare, harp seal.
Sea lions- have short and sparse hair. In the summer, they set up rookeries on rocky islands, where males gather around themselves a harem of 15-20 females, over which fights often break out.
Seals have a thick silky undercoat. Males have a mane on their head and neck. Found near islands, in rookeries. Polygamous: each male has about 50 females in his harem.
Most commercial pinnipeds are of great commercial importance.
Order Cetaceans
The order unites mammalian aquatic organisms that live mainly in the seas. Due to their aquatic lifestyle, the body of these animals is elongated, torpedo-shaped, streamlined, with a disproportionately large head. The hind limbs are absent, the front limbs are turned into flippers, reminiscent of oars. Authority forward movement is a highly developed horizontal caudal fin. There is practically no hair, only some forms have sparse hair on the head. The skin is smooth, without sebaceous and sweat glands. Its top layer is covered with mucus, which reduces resistance when moving in water. There are a pair of mammary glands, their nipples open into pocket-shaped sinuses located in the groin area. There are no pelvic bones, which allows them to give birth to large babies.
Cetaceans have a lot of fat in their bodies. The thickness of the subcutaneous fat layer is large species reaches 50 cm with a total weight of more than 20 tons. This is a kind of fur coat, as well as an abundance of fat in the bones, muscles and body fluids. Protecting the body from hypothermia in cold waters, they reduce its density, which in large forms is close to the density of water.
Cetaceans breathe atmospheric air. Their lung capacity depends on their body size. In relatively small dolphins, the lungs can hold 1-2 liters of air, while in giant dolphins blue whale- about 14 thousand liters. At the same time, the efficiency of its use is high. It is achieved by the development of a number of structural features, including the presence huge amount alveoli, of which, for example, a 1.5-meter dolphin has 3 times more than a person. This allows animals to stretch the pause between respiratory acts, due to which individual species can remain underwater for up to 45 minutes. Breathing is carried out through the nostrils, which are shifted to the crown and open only at the moment of a short act of inhalation and exhalation that occurs after surfacing. When you exhale, steam escapes from the nostrils, and along with it, sprayed splashes of water often fly out, forming a fountain.
The olfactory organs of cetaceans are rudimentary, but vision, touch, and especially hearing are well developed. Toothed whales are capable of echolocation. Dolphins, for example, can emit and perceive ultrasound with a frequency of up to 150-200 kHz. The preferential use of hearing by animals is due to the faster (5 times) propagation of sound vibrations in water compared to air.
Cetaceans breed in water. Their cubs are born developed, large, capable of swimming and following their mother immediately after birth. The body length of a newborn is usually 1/4-1/2 the body length of the parents. For example, black sea dolphin 160-170 cm long gives birth to a calf 80-85 cm long, and a sperm whale 7-8 m long gives birth to 3-3.5 meter long offspring. The newborn emerges from the female reproductive tract with its tail first, and not with its head, as is the case in terrestrial mammals. The relatively short umbilical cord breaks on its own at the time of birth. The mother pushes the newborn to the surface of the water so that he takes his first breath. Toothless whales give birth to one calf every 2-3 years, beluga whales every other year, and dolphins every year. The mother takes care of the offspring and never leaves the baby in trouble. During the period of milk feeding, the young ones grow very quickly, which is associated with the high nutritional value of milk. The calves of large whales gain weight up to 100 kg per day, consuming 250-300 liters of milk daily, which contains up to 50% fat (fat content cow's milk is only 3-4%). At the time of feeding, the baby whale covers the nipple with its tongue rolled into a tube, and the mother squirts milk into its mouth. Whales become sexually mature at the age of 3-6 years, and sometimes later. The lifespan of toothed whales ranges from 20-30 years, some can live up to 35 years.
Suborder toothed whales. They have teeth in the oral cavity. The total number of them in different species of the suborder ranges from 2 to 240, all of them are constructed the same way - with a simple single-vertex crown. The fins are five-fingered. There is no hair on the head.
Representatives: common dolphin, bottlenose dolphin, porpoise, white dolphin, or beluga whale, killer whale, small sperm whale, great sperm whale.
Suborder Toothless, or Baleen whales. The largest mammals on our planet, which have a filtering apparatus in their mouths formed by horny plates (whalebone). Each plate is attached to the upper jaw with its base, and its free part hangs down into the oral cavity devoid of teeth. The basis of baleen whales' food consists of planktonic organisms - crustaceans, the mollusks of which the animal extracts by filtering large masses of water. Occasionally, these whales may feed on small fish. They are found in all oceans and migrate widely. The winter is usually spent in tropical waters, and in the summer they move to cold and temperate waters. warm seas, where plankton develops abundantly at this time. Most baleen whales are giants. The smallest is minke whale- about 10 m, weight about 10 tons. The largest - blue whale– up to 30 m, weighing 160 tons. The stomach of a blue whale can hold up to 1.5 tons of plankton. After 11 months of pregnancy, the female gives birth to one calf 7-8 m long, weighing 2-3 tons. Over 7 months of feeding with milk, the calf grows up to 16 m and has a mass of up to 22 tons. It becomes an adult at 2 years old and grows up to 24 m, weight - about 80t.
Most species of baleen whales are currently under human protection by international agreement.
Cetaceans provide humans with a lot of valuable products. The food industry uses fat and meat. Whale meat contains 20-25% protein, which makes it possible to obtain protein concentrates and dry protein from it, necessary for the production of ice cream, sauces, mayonnaise, etc. The meat of some species is quite suitable for food. Whale oil is used as an additive to vegetable oil in the production of margarine. The connective tissue that remains when the fat is rendered is used to produce gelatin and glue. Vitamins A 1, B 1, B 2, B 12 are obtained from whale liver. The pancreas supplies insulin to a person.
Order Callousfoot
Includes large animals that have a leathery pad (callus) on the third and fourth toes of the front and hind limbs, in front of which there are small, slightly curved horny claw-type formations. The second and fifth fingers are missing. The coat is thick and has a unique structure. It protects animals both from the scorching rays of the sun and from severe cold.
Representatives:
Bactrian camel – found in Mongolia.
dromedary camel(known only in domesticated state).
Camels can go without water and food for a long time; food is stored in the form of fat, which is deposited in the humps, and water, as it turned out quite recently, is stored in the blood, or rather in hygroscopic red blood cells. At the same time, they swell, increasing 3 times in volume. As needed, red blood cells release water to the body's needs. There are other adaptations to life in hot climates.
Guanaco(domesticated form - llama).
Vicuna(domesticated form - alpacas).
Order Proboscis
Includes the largest land mammals, the main distinctive feature which manifests itself in the development of the trunk. The trunk is a skin-muscular formation formed as a result of the fusion of a strongly elongated nose and an elongated upper lip. The body of the representatives of the order is massive, barrel-shaped. Above the ground, it is supported on tall, pedestal-shaped, five-toed legs with small hooves. Small eyes and large ears are placed on the head. The tail is short. The skin is thick and almost hairless. The incisors of the upper jaw grow greatly and protrude from the mouth, forming tusks. There are no fangs. The squad includes two modern looking – African elephant And Indian elephant.
African elephant up to an average height of 3.5 m, weighing about 5 tons. Both males and females have tusks. The ears are large and drooping. They are difficult to tame. Quite numerous
Indian elephants smaller than African ones - up to 3 m. The ears are triangular, thrown back, tusks develop only in males, are easily tamed, but usually do not reproduce in captivity.
Elephants lead a herd lifestyle. Usually the herd is led by an old, experienced female elephant, and only at the moment of “combat operations” does the male take command. Elephants feed on plant foods early in the morning and at night. The elephant gives birth to one sighted calf weighing about 100 kg, which, as soon as it is born, stands on its feet and begins to suck milk. He remains under maternal care until he is 5-6 years old. Sexual maturity is reached after 25 years. Elephants live up to 70 years.
Fossil close to Indian elephant mammoth, who previously lived on the territory of the modern tundra. Its tusks and parts of the skeleton quite often end up in the permafrost layer.
Order Artiodactyls
The order Artiodactyla unites herbivorous mammals of medium and large size, of various physiques, which have a pair of toes on their feet. Of these, the third and fourth are equally well developed, covered with horny sheaths (hooves), the axis of the limb runs between them, and the second and fifth are to one degree or another underdeveloped. When walking, the legs can only move in one plane - forward and backward. There are no collarbones. All artiodactyls are divided into suborders: Non-ruminants And Ruminants.
Ruminants swallow food without chewing, so that later, after regurgitating what they have swallowed, they can calmly chew it thoroughly and swallow it again. In this regard, they have a stomach of four chambers - the first two “store” hastily swallowed matter, and the other two sections receive the chewed mass. Representatives of the suborder constantly move their jaws, as if grinding it, chewing (hence their name). Non-ruminants chew food immediately and have a two-chamber stomach.
Suborder Non-ruminant:
Boar- a large animal, with a short massive body, a thick short neck, a large head, relatively thin limbs and a short tail. The muzzle is elongated and ends with a snout, the ears are long and wide. In males, the upper and lower canines are large, protruding from the mouth, and the molars are tuberculate. The hairline is rough and bristly. It is the ancestor of many breeds of domestic pigs.
Hippopotamus, or hippopotamus– has bare skin and cannot stand drying out. In this regard, hippos spend a lot of time in the water, where they feed on aquatic vegetation.
Suborder Ruminants. Presented deer And bovid.
Deer– medium and large animals with a slender, proportional build. Males usually have branching horns made of bony material, which are shed annually and replaced with new ones. Females, with the exception of reindeer, are antlerless.
Representatives: Noble deer, or maral, sika deer, elk, roe deer.
Bovids united in the vast majority of large ruminants. One of them ( antelope) of light build, and others ( bison) – heavy and massive. A common feature of their structure is horny horns (mainly in males) in the form of hollow sheaths sitting on the grown frontal bones. They persist throughout life.
Representatives: bison, tur, yak, Indian banteng, gayal, buffalo, bison, wild goat, wild sheep, antelope, goitered gazelle, saiga, goral, chamois, giraffe, okapi. Mouflon, argali, bearded, or besar goat- gave rise to the breeds of domestic sheep and goats.
Order Odd-toed ungulates
Mostly large animals of varied structure, in which usually only the third finger is well developed. The axis of the limb passes through it. On the outside, it is covered with a round-shaped horny sheath (hoof). The remaining fingers are less developed or rudimentary. The limbs move only in one plane, there are no collarbones. They can run fast.
Representatives: Przewalski's horse, zebra, wild ass, donkey, white rhinoceros, Indian rhinoceros, tapir
Order Primates
Extremely diverse mammals in appearance. Their body is from 9-12 cm to 2 m long. But despite external differences, they are united by many common features buildings. Thus, the skull is relatively large, the eye sockets are almost always directed forward, thumb opposed to the others. Fingernails. Hind legs plantigrade, and the anterior prehensile. Nipples (from 1 to 3 pairs) are located on the chest. There are all groups of teeth, with 2 pairs of incisors. Primates are divided into two suborders: Prosimians And Monkey.
Suborder Prosimians, or Lesser primates. They include primates up to 106 cm. Some have a long, densely pubescent tail, but not prehensile, while others have almost no pubescence or are absent. The most primitive among them - tupai - are close in structure to ancient insectivorous mammals. More advanced ones - lemurs and tarsiers - lead an arboreal lifestyle and are active at night.
Representatives: tupaya, slender loris, lemur, tarsier.
Suborder Monkey, or Great apes. They unite the most highly organized animals on our planet. Their brain is relatively large, the forebrain hemispheres in the vast majority of species have numerous grooves and convolutions. The tail is absent or developed to varying degrees. The thumb is clearly opposed to the rest. Body length from 15 to 200 cm. Most interesting among higher primates monkeys And great apes. Monkeys have developed cheek pouches, ischial calluses, and a usually long tail. Many of them lead an arboreal lifestyle, but they also look for food on the ground. Very active, noisy animals, screaming for any reason. They move along the ground and along thick branches on four legs, resting on the surface with the palms of their hands and the entire sole of their hind legs.
Representatives: monkeys, baboons, macaques.
Great apes include the highest representatives of the squad. Their brain skull is especially developed. The forebrain hemispheres have complex sulci and convolutions. There is no tail or ischial calluses. All apes live in forests, easily climb trees, and their adaptations for moving on the ground are imperfect. When walking, they do not place their feet on the entire sole, but only on the outer edge of the foot. Helps with movement and balance Long hands, with which the animal rests on the ground with the back of its bent fingers. They live alone and in groups.
Representatives: orangutan, chimpanzee, gorilla, gibbon.
Belongs to the higher primates Human. However, it differs qualitatively from all other animals in the development of labor activity, articulate speech and public life, consciousness.
Infraclass: Eutheria, Placentalia Gill, 1872 = Placentals, higher animals
- Taxonomy: Superorder: Ungulata = Ungulates
- Order: Artiodactyla Owen, 1848 = Artiodactyla, even-toed
- Order: Perissodactyla Owen, 1848 = Odd-toed, odd-toed
Mammals (or Animals) are the highest class of vertebrate animals, crowning the entire system of the animal world. There are more than 4,000 species of living mammals.
The skin is rich in glands that have diverse and very important functional significance. Particularly characteristic are the mammary (mammary) glands, which are not even hinted at in other vertebrates. The lower jaw consists of only one (dentary) bone. In the middle ear cavity there are three (and not one, as in amphibians, reptiles and birds) auditory ossicles: the malleus, the incus and the stapes. The teeth are differentiated into incisors, canines and molars; they sit in the alveoli. The heart, like that of birds, is four-chambered, with one (left) aortic arch. Red blood cells are without nuclei, which increases their oxygen capacity. Mammals are distributed almost throughout the entire Earth: they are not found only on the Antarctic continent, although seals and whales live off its coast. In the area of the North Pole there are polar bears, pinnipeds, and cetaceans (narwhals). Mammals are also widely distributed in living environments. Suffice it to remember that, along with terrestrial species 
We, which are the majority, a number of species are in one way or another associated 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 produced such a variety of forms as mammals. The degree and nature of relationships with living environments are different. Some animals live in very diverse environments. For example, the common fox is common in forests, steppes, deserts and mountainous areas. Wolves live in even more diverse conditions (in addition to the indicated zones for foxes, wolves are also found in the tundra). Naturally, such animals do not have clearly defined adaptations to life in any particular environment. Along with this, the specific habitat determines many of the characteristics of animals. Among the inhabitants
tropical forestsThe vast majority of mammals belong to the placental subclass, including all animals living in Russia.
They differ in the nature of reproduction and development of embryos that develop in the uterus. A close connection is established between the embryo and the walls of the mother’s uterus with the help of a special formation - the placenta ( children's place). Through the placenta and umbilical cord, both nutrients and oxygen enter the embryo's body from the mother's body. This allows the placental mammal embryo to remain in the mother's uterus relatively for a long time and achieve more complete development than embryos of marsupials.
Placentals do not have a bursa. The jaws bear teeth, usually clearly divided into incisors, canines and molars.
Zoologists divide the placental subclass into a number of orders, of which we will describe only the main ones:
· Order insectivores
The order Insectivores includes hedgehogs, moles, and shrews. These are small animals with a number of primitive structural features. The 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, with which the animals sniff surrounding objects.
Order Chiroptera (bats)
Bats are the only group of mammals whose representatives are capable of active flight. Their wings are formed by a thin flight membrane stretched between the elongated fingers of the forelimbs and hind legs, as well as between the legs and tail. The flapping movements of the wings are carried out by contracting powerful pectoral muscles, attached to the sternum, on which there is (like in birds) a longitudinal keel.
Bats are nocturnal animals, hiding during the day in caves, attics, hollows and other shelters. In these same places they hide for the winter, which they spend in a state of deep hibernation; some species fly to warm countries. When flying in the dark, bats use auditory location: they emit intermittent high-frequency sounds (not audible to the human ear) and perceive their echoes reflected by various objects. This allows them to avoid collisions with obstacles in the dark and catch flying insects. Bats bring great benefits by exterminating harmful nocturnal insects (usually inaccessible to birds). In tropical countries there are large fruit-eating fruit bats (reaching a wingspan of 1.5 m).
· Squad of predators
The order of predators includes wolves, foxes, arctic foxes, dogs, lions, tigers, leopards, lynxes, wild and domestic cats, sables, martens, ferrets, minks, otters, stoats, weasels, hyenas, and bears.
Most of these animals eat the meat of various animals, birds and fish. But some of them (for example, bears) eat both animal and plant foods. The teeth of predatory animals are usually adapted for grasping, killing and tearing their prey. Small incisors are chisel-shaped. Behind them protrudes very large conical fangs, with which predators hold and kill their prey. Molars with rows of sharp or (less often) blunt tubercles are adapted to separating pieces of meat rather than chewing food - so predators usually swallow it in large pieces. One of the molars of each jaw reaches a particularly large size and bears large tubercles - these teeth are called carnassial.
· Order Pinnipeds
covers different types seals, walruses, fur seals, sea lions. The life of these animals is closely connected with the aquatic environment, which determined many of the features of their organization. The body is usually torpedo-shaped and streamlined. The limbs are turned into flippers and serve as fins. The hairline in most species is reduced to one degree or another. A thick layer of fat is deposited under the skin.
Pinnipeds spend most of their lives at sea (some forms live in large lakes), but their young are always born and raised on the shore or on ice. They feed on fish and other aquatic animals. They serve as a commercial object, as they provide valuable lard, leather or fur skins, and meat.
· Order Cetaceans
The order Cetaceans includes different kinds whales and dolphins. The structure of marine animals shows signs of adaptation to life in aquatic environment which they never leave. Streamlined body. The forelimbs look like flippers, the hind limbs are atrophied. At the end of the body there is a horizontal caudal fin. The skin is bare, underneath there is a thick layer of fat. There are toothed and toothless whales.
Toothed cetaceans include dolphins and sperm whales. Their jaws bear teeth (sperm whales have teeth only on the lower jaw). They feed mainly on fish and cephalopods. Toothless whales have no teeth, but the mouth has a special filtering apparatus made of rows of horny plates hanging from the roof of the mouth (the so-called baleen) with a fringe of fibers. By filtering water through rows of these plates, whales catch various small animals (mainly crustaceans) on which they feed.
Whales and dolphins give birth to their young and nurse them with milk in the water.
Whaling, which is now concentrated mainly in Antarctica, provides valuable fat, meat and a number of other products.
· Squad of rodents
Rodents. The most species-rich order of mammals. Rodents include squirrels, gophers, marmots, dormice, jerboas, beavers, hamsters, various voles, mice, rats, etc. General sign All rodents have a unique structure of teeth. In the upper and lower jaws there is only one pair of large chisel-shaped incisors with constant growth. Animals use them to gnaw solid food. There are no fangs. The molars are separated from the incisors by wide toothless spaces. Molars are adapted to grinding hard food; they have a flattened chewing surface with tubercles or enamel ridges and folds.
Among rodents there are many plant pests - gophers, hamsters, voles, mice, etc. But certain species produce valuable fur pelts and therefore serve as commercial objects (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 Lagomorpha
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 bears two pairs of incisors, of which the front ones are large, chisel-shaped, and the rear ones are small, column-shaped. Hares are the favorite prey of hunters. Rabbits are bred for their meat and skins.
· Order artiodactyls
The order of artiodactyls includes: from wild animals - various types of bulls, mountain goats and sheep, antelopes, deer, camels, wild boars, hippopotamuses and other animals, and from agricultural animals - large cattle, sheep, goats, pigs, reindeer, camels. All of these animals have feet with either two or four toes. The first finger is always atrophied. In those species whose limbs have four fingers, both lateral ones are usually underdeveloped and significantly smaller than the two middle ones. The ends of the toes are covered with durable horny covers - hooves, which protect them from damage when hitting the ground during fast running.
Cattle, sheep, goats and many wild artiodactyls belong to the group of ruminants. The digestive process of these animals is unique. The stomach has 4 chambers: the rumen, the mesh, the book and the abomasum.
· Order equids
Even-toed ungulates include horses, zebras, donkeys, and rhinoceroses. Like artiodactyls, the ends of the fingers of these animals are covered with horny sheaths - hooves. The third (middle) finger is the most developed, while the other fingers are less developed or vestigial. Horses and donkeys bred in our country have only one middle finger on each leg.
Domestic horses are bred from an extinct wild horse, the tarpan, which is very similar to Przewalski's horse. Nowadays, many different breeds of horses have been created - heavy-duty, draft, and riding horses.
In the deserts of Central Asia, in some places, kulans have been preserved - animals that combine the characteristics of horses and donkeys. Domestic donkeys are bred in many southern regions our country as draft and riding animals.
The forests and savannas of Africa and South Asia are inhabited by huge rhinoceroses. They have three toes on their feet. Fat leather carries rare rough hair. There are one or two sharp marks on the nose and forehead horns.
· Order proboscis
Representatives of the proboscis order - African and Indian elephants. These huge animals (weighing up to 5 tons) are characterized by big trunk, five-toed feet (each finger of which is covered with a hoof), huge incisors of the upper jaw, turned into a pair of tusks, thick, almost bare skin. 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.
· Order primates
Primates, the group of mammals closest to humans. They are distinguished by the strong development of the brain, especially its hemispheres, which have complex system grooves and convolutions. On the paws, as on the human hands, the thumb is opposed to the other, which makes it easier for them to grasp branches when climbing. The fingers bear nails at the ends. 2 pairs of incisors.
Monkeys are found in tropical and subtropical countries. They usually live in flocks. They feed on a variety of animal and plant foods.
Particularly interesting is the group of great apes (chimpanzees, gorillas, orangutans, etc.), which in a number of characteristics are closest to humans.
According to its anatomical structure, humans also belong to this order. Its similarities and differences with other mammals, in particular monkeys, are described in the next section.