marsupial mammals. Numbat is an ancient marsupial animal. Overseas relatives of marsupials

Everyone knows that Australia is the world of marsupial mammals. On the smallest continent of the planet, there is simply an amazing variety of these animals. In addition to the well-known kangaroos and koalas, couscous, wombats, marsupial martens, jerboas, rats, mice, anteaters, moles and even wolves live in Australia. Marsupials also live in regions adjacent to Australia - on the islands of New Guinea. But marsupials, although not in such abundance, are also found on the American continent.

As paleontological studies show, even during the Mesozoic, marsupials lived almost all over the globe. Marsupials and other primitive mammals (oviparous) represented at that time the pinnacle of the evolution of the terrestrial animal world. But over time, more developed mammals began to appear - placental animals, which, as scientists believe, replaced marsupials from all continents except Australia and South America, about 20 million years ago. Australia by the time placental mammals appeared was already isolated from the rest of the world, so its animal world remained practically unchanged. But the fate of the marsupials of South America is quite interesting. Here they lived all over the continent by the time the connection between North and South America arose. And it happened about 12 million years ago. North American species began to penetrate into South America, and almost all marsupials, unable to withstand competition with them, disappeared. Only opossums and coenolests remained here.

In the photo: virginian opossum (cubs love to ride on their mother's back)

Possums not only survived, but also populated vast areas of North America, where they thrive to this day. The Virginian opossum, common in North America, is a rather cute animal, about the size of a domestic cat. It lives along the west and east coasts to the Canadian border. Opossums are excellent tree climbers and are predominantly nocturnal. They eat very diversely: from fruits, berries and nuts to small insects, frogs and snakes. These animals do not miss the opportunity to delve into the garbage if they live near human habitation. But the endurance and vitality of the Virginian opossums is beyond praise. They are resistant to the venom of the rattlesnake and some other snakes of the American continent, have excellent immunity and are not susceptible to many diseases, including rabies.

In addition to possums, another marsupial lives in the New World, representatives of the coenolest family, but they are common only in South America, in the Andes. Caenolestovye, they are also called rat-like opossums, outwardly resemble mice or shrews. They live in mountain forests no higher than 4,000 meters. These animals are also active at night, and according to the type of food they belong to insectivorous animals. They are not as numerous as opossums.

So, it turns out that their distant relatives live thousands of kilometers from Australia. And opossums are not only preserved, but also actively expanding their range, moving further and further north.

Around 1500, the traveler Vicente Pinson brought a New World possum to the Spanish royal court and persuaded the king and queen to put their hand in the animal's bag. This was the first official acquaintance of Europe with animals, named marsupials for a bag-like formation on the stomach.

Cubs of marsupials are born underdeveloped, and their further development takes place in the bag.

However, not all marsupial species have a typical bag. A "finished" pocket-type bag is found in koalas, kangaroos, and large American opossums. In the comb-tailed mulgara mouse, skin folds play the role of a bag. Rat opossums and the marsupial anteater do not have a pouch at all. Newborns of these species are protected only by the mother's fur. The mother carries the grown up, but still feeding cubs on her back.

There are about 250 species of marsupial mammals - from marsupial mice 12 cm long to kangaroos reaching more than 2 m. The geographical distribution of marsupials is very uneven. They are found in Australia and nearby areas, where they are most numerous and diverse, as well as in North and South America.

Baby marsupials are born amazingly small. A newborn marsupial mouse is the size of a grain of rice, a koala is from a bumblebee. In most species, not all internal organs are developed at birth, the not fully formed hind limbs are bent and almost invisible. But this tiny creature has an excellent sense of smell, its mouth is wide open, and the front legs are well developed, and the cub is able to crawl quite briskly. Whether he survives depends on the grip, because he needs to crawl through the wool on his mother's belly a relatively long distance to the bag where the milk is waiting without help. Having found the nipple, the cub takes it into its mouth and holds on so tightly that it is very difficult to separate it without damage.

The methods of movement of marsupials are very different, which is not surprising with so many species. In most, the hind limbs are larger and stronger than the forelimbs. However, in arboreal and burrowing species, the hind and forelimbs are more proportionally developed. Koalas and opossums are excellent tree climbers thanks to their very mobile limbs with soft pads and sharp claws. This also applies to squirrel-like marsupial flying squirrels, which can fly (glide) using skin folds on the sides of the body.

Wombats and marsupial moles dig holes with powerful front paws with spatulate claws. Tearing the ground, the mole fills up the passage with its hind limbs. Sometimes it travels on the surface of the earth for short distances. A stocky, badger-sized wombat digs tunnels up to 30 m long.

Another thing is kangaroos, which jump on their hind legs, using their tail to maintain balance at high speed, or on all four limbs, and then the tail serves as an additional point of support. In open spaces, large kangaroos can move very quickly: their speed reaches 65 km / h, while the length of the jumps is 7.5 m or more.

The Virginian opossum, when threatened, first hisses and then releases a foul-smelling liquid. But if these tricks do not scare off the attacker, the opossum falls into a kind of coma. He lies motionless, his tongue hanging out, his limbs becoming stiff and losing visible sensitivity, his breathing and heartbeat slow down so that they are almost imperceptible. This happens in moments of danger, but even under normal conditions, the metabolism of opossums and other marsupials is less intense than that of placental mammals, the body temperature is lower, and the heart beats less frequently.

The first European colonists in Australia gave names to local animals after their resemblance to European ones. The marsupial mouse, marsupial marten, marsupial wolf look and behave like the corresponding placental mammals. Even scientists have followed this erroneous tradition. For example, the Latin name koala translates as "marsupial bear", but these charming little animals, although outwardly reminiscent of teddy bears, are still closer to leaf-eating forest monkeys in their lifestyle and habits. Marsupials in Australia occupy a variety of ecological niches - just like placental mammals elsewhere. Kangaroos and wallabies are large herbivores. Wombats and marsupial moles are burrowers. Tasmanian marsupial devils and nearly extinct marsupial wolves are carnivores. The most numerous are insectivorous species, such as marsupial anteaters, fluffy and striped couscous.

The large red kangaroo dominates the wild herbivores of the Australian steppes. Females are smaller than males, which weigh more than 90 kg and arrange "fistfights" among themselves.

The Tasmanian wolf, the largest marsupial predator, is on the verge of extinction. In pursuit of prey, including kangaroos, he prevails not with speed, but with endurance.

Marsupial mice, or mice, feed on insects and other small animals. Thanks to the flattened head, they are able to climb into narrow cracks.

The giant marsupial marten, with its long body and short, tenacious paws, deftly climbs trees, but sometimes descends to the ground. It feeds on small animals and eggs, and hunts mainly at night.

The marsupial anteater feeds mainly on ants and termites, opening their dwellings with forepaws with powerful claws and thrusting a long muzzle with a sticky tongue inside.

The marsupial mole rarely appears on the surface. He digs the ground with his claws in search of worms and insects, which he finds by touch.

The content of the article

marsupials(Marsupialia), an extensive group of mammals, differing from placental, or higher animals, in features of anatomy and reproduction. Classification schemes vary, but many zoologists consider marsupials as a superorder, allocated to a special subclass of Metatheria (lower animals). The name of the group comes from the Greek. marsupios - a bag, or a small bag. Marsupials are common in Australia and New Guinea, as well as in North and South America, from southeast Canada to Argentina. Wallabies are introduced to New Zealand, Great Britain, Germany, the Hawaiian Islands, and opossums are introduced to the west of North America, where they settled from southwest British Columbia to northern California.

The taxonomy of the group varies, but its modern representatives are usually divided into 16 families, 71 genera and 258 species, most of which (165) live in Australia and New Guinea. The smallest marsupials are the honey badger possum ( Tarsipes rostratus) and marsupial mouse ( Planigale subtilissima). The body length of the first reaches 85 mm plus 100 mm tail with a weight of 7 g in males and 10 g in females. The total body length of a marsupial mouse is up to 100 mm, and about half of it falls on the tail, and its weight is 10 g. The largest marsupial is a large gray kangaroo ( Macropus giganteus) with a height of 1.5 m and a mass of 80 kg.

A bag.

Marsupials give birth to very small cubs - their mass does not reach even 800 mg. The duration of feeding of newborns always exceeds the gestation period, which is from 12 to 37 days. During the first half of the feeding period, each calf is permanently attached to one of the teats. Its end, once in the round mouth opening of the baby, thickens inside, providing a strong connection.

In most species, the nipples are located inside a pouch formed by folds of skin on the mother's abdomen. The pouch opens forward or backward depending on the species and can be closed tightly due to the contraction of the muscle fibers. Some small species do not have a bag, but newborns are also constantly attached to the nipples, the muscles of which, by contracting, pull the cubs close to the mother's stomach.

The structure of the reproductive organs.

Modern mammals are divided into three groups, usually considered separate subclasses: monotremes (platypus and other oviparous), marsupials and placentals (dogs, monkeys, horses, etc.). This terminology is not entirely successful, since the placenta - a temporary internal organ that connects the mother to the developing embryo before its birth - is also formed in marsupials, although in most cases it has a less complex structure.

One of the anatomical features that distinguish these three groups of mammals concerns the location of their ureters and genital tracts. In monotremes, like in reptiles and birds, the ureters and genital ducts drain into the upper part of the rectum, which forms a common excretory chamber called the cloaca. Through the "one pass" from the body are excreted and urine, and genital products, and feces.

The marsupial and placental excretory chambers have two - the upper (rectum) for feces and the lower (genitourinary sinus) - for urine and genital products, and the ureters flow into a special bladder.

Moving in the course of evolution to a lower position, the ureters either pass between the two genital ducts or go around them from the outside. In marsupials, the first variant is observed, in placental - the second. This seemingly small feature clearly separates the two groups and leads to profound differences in the anatomy of the organs of reproduction and its methods.

In female marsupials, the urogenital opening leads to a paired reproductive organ, consisting of two so-called. lateral sheaths and two uteruses. These vaginas are separated by the ureters and cannot merge, as in the placental ones, but are connected in front of the uterus, forming a special chamber - the so-called. middle vagina.

The lateral sheaths serve only to carry the seed to the uterus and are not involved in the birth of the cubs. During childbirth, the fetus passes from the uterus directly into the median vagina and then, through the birth canal, which is specially formed in the thickness of the connective tissue, into the urogenital sinus and out. In most species this canal closes after giving birth, but in some kangaroos and honey badger possums it remains open.

In males of most marsupial species, the penis is bifurcated, probably to direct the seed into both lateral sheaths.

evolutionary history.

In addition to the characteristics of reproduction, there are other differences between marsupials and placentals. The former do not have a corpus callosum, i.e. a layer of nerve fibers that connects the right and left hemispheres of the brain and produces heat (thermogenic) brown fat in young, but there is a special shell membrane around the egg. The number of chromosomes in marsupials ranges from 10 to 32, while in placentals it usually exceeds 40. These two groups also differ in the structure of the skeleton and teeth, which helps to identify their fossils.

The presence of these features, supported by persistent biochemical differences (amino acid sequences in myoglobin and hemoglobin), suggests that marsupials and placentals are representatives of two long-separated evolutionary branches, whose common ancestors lived in the Cretaceous period ca. 120 million years ago. The oldest known marsupials date from the Upper Cretaceous of North America. Remains dating from the same era have also been found in South America, which was connected to the Northern Isthmus during most of the Cretaceous.

At the beginning of the Tertiary period (about 60 million years ago), marsupials settled from North America to Europe, North Africa and Central Asia, but died out on these continents about 20 million years ago. During this time in South America they reached a great diversity, and when it reconnected with North America in the Pliocene (about 12 million years ago), many species of opossums penetrated from there to the north. From one of them came the virginian opossum ( Didelphis virginiana), which spread through the east of North America relatively recently - approx. 4000 years ago.

Probably, marsupials came to Australia from South America through Antarctica, when these three continents were still interconnected, i.e. more than 50 million years ago. Their first finds in Australia date back to the Oligocene (about 25 million years ago), but they are already so diverse that one can speak of a powerful adaptive radiation that occurred after the separation of Australia from Antarctica. Nothing is known about the early history of Australian marsupials, but by the Miocene (15 million years ago), representatives of all modern, as well as their extinct families, appear. The latter include several large rhinoceros-sized herbivores ( Diprotodon and Zygomataurus), giant kangaroos ( Procoptodon and Sthenurus) and large predators, for example, similar to a lion Thylacoleo and wolf-like Thylacinus.

At present, the marsupials of Australia and New Guinea occupy the same ecological niches as placentals on other continents. marsupial devil ( Sarcophilus) is similar to the wolverine; marsupial mice, rats and martens are similar to mongooses, weasels and shrews; wombat - woodchuck; small wallabies - to rabbits; and large kangaroos correspond to antelopes.

Marsupials ( Marsupialia) are a group (infraclass) of mammals. Like most other mammalian species, they give birth to live young, but only at an early stage of development. In some species, such as bandicoots ( Peramelemorphia), the gestation period is as short as 12 days. Newborn baby marsupials crawl over the mother's body into a bag located on her stomach. Once inside the pouch, the baby attaches itself to the mother's nipple and feeds on milk until it is large enough to live in the outside world.

While large marsupials tend to give birth to a single young, smaller species are more likely to produce large litters.

Marsupials were common in many areas during and outnumbered placental mammals. Today, the only living marsupial in North America is the opossum.

Marsupials first appear in the record from during the Late Paleocene. They later appear in the fossil record from during the Oligocene, where they diversified during the early Miocene. The first large marsupials appeared during the Pliocene.

Distribution map of modern marsupials/Wikipedia

Today, marsupials remain one of the dominant mammal groups in South America and Australia. In Australia, the lack of competition has led marsupials to be able to diversify and specialize. Today the continent is inhabited by insectivorous marsupials, carnivorous marsupials, and herbivorous marsupials. Most South American marsupial species are small and arboreal.

The reproductive tract of female marsupials differs from placental mammals. They have two vaginas and two uteri, while placental mammals have one uterus and one vagina. Male marsupials also have distinctive features of the genital organs - they have a bifurcated penis. The brain of marsupials is also unique, it is smaller than that of placental mammals, there is no corpus callosum and nerve pathways that connect the two hemispheres of the brain.

Marsupials are very diverse in appearance. Many species have long hind legs and elongated snouts. The smallest species of marsupial is the northern marsupial, while the largest is the red kangaroo. To date, there are about 334 species of marsupial mammals, of which 70% of the species are found on the Australian continent (including Tasmania, New Guinea and nearby islands). The remaining 100 species are found in the Americas - mostly in South America, thirteen in Central America and one in North America, north of Mexico.

Classification

Marsupials are classified in the following taxonomic hierarchy:

⇒ ⇒ ⇒ ⇒ ⇒ ⇒ Marsupials

Marsupials are divided into two modern superorders and seven orders:

• Superorder American marsupials ( Ameridelphia) - there are about 100 species of marsupials living today. The American marsupials are the older of the two modern groups, which means that the members of this group migrated to Australia and diversified. Superorder Ameridelphia subdivided into the following two divisions:
  • Possum Squad ( Didelphimorphia);
  • Caenoleste detachment ( Paucituberculata).

• Superorder Australian marsupials ( Australidelphia) - there are more than 200 species of Australian marsupials living today. Members of this group include Tasmanian devils, marsupial anteaters, bandicoots, wombats, marsupial moles, pygmy opossums, koalas, kangaroos, wallabies, and many other species. Australian marsupials are divided into five orders:
  • Detachment Microbiota ( Microbiotheria), found in South America;
  • Squad Marsupial moles ( Notoryctemorphia);
  • Order Predatory marsupials ( Dasyuromorphia);
  • Bandicoot Squad ( Peramelemorphia);
  • Detachment Dicissus marsupials ( Diprotodontia), includes most of the modern marsupial species.

For most people, Australia is a continent where marsupials live, which are not like those that everyone is used to seeing.

The marsupials of Australia differ in appearance, have a different physiology and a different body structure. Females have a pouch on their belly where they carry their undeveloped young.

Currently, there are about 250 species of marsupials.

The main difference between marsupials is that their cubs are born underdeveloped and for several months they grow, being in this very bag on the mother's stomach. Even when they grow up and can move and eat on their own, they do not part with the bag and hide in it at the slightest danger. This continues until his younger brother takes his place.

The fauna of Australia is very diverse. There are several dozen animals in Australia, and they are mostly marsupials. The most famous of this order is the kangaroo. Probably everyone is familiar with this animal, although by hearsay, because the kangaroo is a kind of visiting card of Australia. Kangaroo is found only in Australia, with the exception of a few species settled on the islands of Oceania.

In general, there are several types of kangaroos. The most famous is the large red kangaroo. Large red kangaroos reach a height of 2 meters and a weight of up to 80 kg or more. As you know, kangaroos move by jumping, and so the jumps of a red kangaroo can be up to 10 m long. And these jumpers can overcome up to 3 meters in height. "Redheads" live mainly in flat places such as "savannas". They eat plant foods.

The second type is the gray "gigantic" or forest kangaroo. These kangaroos are slightly smaller in size, but not agile. A gray kangaroo can easily reach speeds of up to 65 km / h. So hunters, even by car, cannot always catch up with him. Although, in principle, the “Big Gray”, although of an impressive size, is quite a peaceful and trusting animal.

The third species is the mountain kangaroo "Vallaroo". They have a more massive physique and relatively short hind legs - this is perhaps the most dexterous of the kangaroos. They live in mountainous areas and easily jump from rock to rock and along mountain steeps, perhaps better than any mountain goat.

There is a species of kangaroo that lives in trees. They are somewhat different from those living on earth. This is understandable, because climbing trees needs its own characteristics. But, nevertheless, these are just as interesting creatures and they also carry their children in a bag.

They live in Australia and very small kangaroos. Rather, it is something between a kangaroo and a rat. They are called quokka. They are somewhat similar to our jerboas, but also marsupials. These herbivores are very shy and are mostly nocturnal.

No less interesting is another representative of the Australian marsupials, the marsupial koala bear. Very cute, looks like a teddy bear. The koala lives in eucalyptus groves. He spends all his time in the trees. He does not drink water, because he eats eucalyptus leaves, and their juice is enough for him. Koalas do not recognize other food.

The marsupial family also has the largest burrowing animal, the wombat. Outwardly, he looks like a small bear, but he is a herbivore. An adult wombat reaches a meter or more in length, and can weigh more than 40 kg.

There is another amazing mammal in Australia - the marsupial anteater nambat. This is a fairly beautiful animal, ranging in size from 20 to 30 cm with striped coloration. In principle, it is a predator, because it feeds on living beings. His food is termites. Nambat belongs to the class of marsupials, although it does not have a bag as such. On his stomach is a milky field, framed by curly hair. Newborn naked and blind cubs, clinging to wool, hang on the nipples and live like this for almost 4 months. When they become larger, the female leaves them in a hole or in a hollow and feeds them at night, because she is very shy.

One of the rare marsupials is the spotted marsupial marten. This beautiful animal is a real predator that feeds on everything that is smaller than it in size: rabbits, birds, it can eat both a snake and fish, well, everything that comes across. The marten is more than half a meter long and can weigh up to 10 kg. In the spotted marsupial marten, the brood pouch is not permanent. It develops during the breeding season, is located behind and opens towards the tail. Normally, it's just a fold of skin. Unfortunately, this animal is on the verge of extinction and can only be found in national parks.

Another of the now rare marsupials is the rabbit bandicoot. Outwardly, bandicoots are similar to rats, only they have a more elongated muzzle, and their ears are large, like those of a hare. These animals are up to 45 centimeters long, plus a tail up to 20 cm. Bandicoots, or as they are called bilbies in another way, feed on everything that gets. They can eat both insects and their larvae, easily cope with small lizards and other living creatures. But they can also make do with various roots, mushrooms and other plant foods.

Previously, many marsupial predators, called the marsupial devil, lived in Australia. This is a rather unpleasant vicious and foul-smelling animal. Appearance corresponds to its name. But over time, this beast was replaced by the Dingo dog, and now the marsupial devil can only be seen in the zoo. In the wild, it can only be seen in Tasmania, where it is called the Tasmanian devil.

Of course, in such a brief review it is impossible to talk about all the marsupials living in Australia, but we hope that the information obtained in this article gives a general idea of ​​​​these amazing animals living only on this sunny continent.