Man and woman 

Who eats eucalyptus which animal. Slow motion world of koalas and sloths. Traditional medicine recipes

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Scientists have sequenced the complete genome of a koala for the first time and analyzed more than 26,000 active genes. Nature Genetics. This allowed scientists to understand why marsupials can eat poisonous eucalyptus leaves without harm to themselves, how they chose the right diet for themselves, and how they learned to protect cubs and adults from infections.

Koala ( Phascolarctos cinereus) to date, the only representative of the koala family that lives in Australia. Koalas are the closest relatives of wombats, their common ancestor lived about 30–40 million years ago. In ancient times, 15-20 species of these animals existed on the continent, and the current species appeared about 350 thousand years ago. To date, three subspecies are known. One of them lives in Queensland, in the northeast of the continent, the other two live in the south and southeast of the country. Previous studies (although more than 20 years old) have shown that two of the three subspecies have low genetic diversity and a high percentage of inbreeding.

The female koala gives birth to an underdeveloped calf after a 35-day pregnancy, and the baby spends the next six months in the mother's brood pouch. Koalas are very selective in food: they feed almost exclusively on eucalyptus leaves, and out of 600 species of eucalyptus trees they prefer about 30. Animals get almost all the water from the leaves, so they include in the diet those types of eucalyptus whose leaves contain at least 55 percent water. Since the leaves are low in calories, animals need to eat up to 400 grams of leaves per day and save energy. They sleep about 20 hours a day and eat most of the remaining four hours. Eucalyptus leaves are not a very attractive food, not only because of their low calorie content. They contain compounds that are extremely poisonous to most other animals. Koalas, on the other hand, adapted to them, and thereby practically avoided food competition. However, how they adapted to poisonous food, and how they differentiate suitable trees among the vast variety of eucalyptus species, has not yet been clear.

To answer these questions and more (such as how koalas protect themselves from infections and how the species can be saved in the future), scientists from the Koala Genome Consortium sequenced the complete genome of the marsupial bear. The research team, now composed of 54 scientists from seven countries, led by Dr. Rebecca Johnson, began work in 2013 and has already published part of the results.

In the new work, scientists present directly the results of genome sequencing and analysis of the 26,558 active genes that make up it. The genome of koalas turned out to be larger than the human one (3.42 versus 3.2 billion base pairs), but consists of a smaller number of chromosomes (16 versus 23 pairs).

Scientists have discovered how marsupials have adapted to their toxic diet. They turned out to have much more genes encoding proteins from the cytochrome P450 family than other animals. These enzymes oxidize various substances, converting them into water-soluble metabolites that are rapidly excreted in the urine. It turned out that in koalas, cytochromes are produced in many tissues, including the liver. However, the defense turned out to have a downside - cytochromes quickly break down antibiotics that are given to sick koalas.

The genes also helped to explain the ability of animals to recognize the desired types of eucalyptus. Koalas have 24 genes responsible for recognizing bitter tastes - the largest number among Australian marsupials. In addition, they turned out to have six genes encoding vomeronasal receptors that can detect the smell of not too volatile substances. For comparison, the marsupial devil and the gray short-tailed opossum each have one such gene, while the platypus and wallaby do not have them at all. Koalas are also able to feel the "taste of water" - to recognize the water content in eucalyptus leaves. They learned this by increasing the genes for a protein called aquaporin 5, which forms pores in the cell membrane through which water enters the cells.

Researchers have found that koalas protect their babies from infections while they are sitting in a pouch with the help of breast milk. It contains enzymes specific only for koalas, which have an antimicrobial effect. They protect young animals from a range of bacterial and fungal infections, including chlamydia. Chlamydia pecorum, that cause diseases of the eyes and genitourinary system. Adult koalas are saved from infections with the help of numerous proteins of the immune system - immunoglobulins, proteins of the major histocompatibility complex, T-lymphocytes.

In addition, scientists have found new genetic markers and with their help made sure that subspecies, which, according to old studies, had low genetic diversity and a large percentage of inbreeding due to the isolation of populations, actually mix with each other and their genetic diversity is quite high.

More details about the habits and personal life of koalas Zhenya Timonova in one of the issues "Everything is like animals."

Ekaterina Rusakova

These funny little animals, photos of which can be seen in various publications about animals, are of interest not only to ordinary lovers of unusual inhabitants of our planet, but also to scientists. Where does the koala live? What does it eat? What lifestyle do you prefer? We will not leave any of these questions unanswered in our article. We hope that many facts from the life of these charming creatures will be of interest to you.

What continent does the koala live on?

The koala is an animal that is endemic to Australia. This is the original representative of the Koalov family. They live in eucalyptus trees. The koala is a marsupial animal belonging to the group of two-cutters. Its range is mainland Australia, but only its eastern and southern parts.

Before the arrival of Europeans, animals were common in the north and west. Much later, koalas were inhabited by humans on the territory of Kangaroo Island. Small animals, similar to teddy bears, cause universal sympathy. These marsupials spend almost their entire lives on trees, deftly walking along the branches. A koala can live on one tree for many days, and only after cleaning its foliage does it change its “home”.

You can’t run far on the ground on short legs, which is why slow koalas often die under the wheels of cars or become easy prey for wild dingo dogs. Animals spend the night hours feeding, and the rest of the time they doze, comfortably nestled in a fork in the branches. Koalas sleep very sensitively and wake up at the slightest rustle. They prefer to live alone. Each adult animal has its own lands, which it marks with secretions of odorous glands. Such a plot of a male sometimes coincides with the possessions of several females.

What does a koala look like?

These are small animals: their body size is from sixty to eighty centimeters, with a weight of six to fifteen kilograms. The tail of the koalas is very small: it is almost invisible behind the lush fur. The animal has funny rounded ears that are completely covered with fur.

It is impossible to describe what a koala looks like without mentioning the fur of these animals. It is soft and thick, quite durable. The color can be different, but most often shades of gray predominate. Much less often you can meet an animal with bright red-red fur.

Lifestyle

We found out where the koala lives and what it looks like. It's time to tell how these animals live. Koalas are animals leading a measured and leisurely lifestyle. Almost all day (from 18 to 22 hours) they sleep. Teddy bears are active at night, which lasts no more than two hours. As a rule, this is due to the need to find food for themselves.

It's funny that during the so-called periods of wakefulness, koalas practically do not move: they just sit on the branches, holding on to the trunk with their forelimbs. At the same time, the koala sometimes shows enviable grace and lightness, deftly jumping from one tree (where all the food is eaten) to another.

Nutrition

As scientists have found out, such a leisurely lifestyle of koalas is not accidental. It has to do with their diet. What do koalas eat? Why does nutrition have such an impact on their lifestyle? Knowing where koalas live, answering these questions is easy. The diet of these animals includes only eucalyptus leaves and shoots, which contain almost no proteins. In addition, eucalyptus leaves are deadly for the vast majority of animals. This is due to the content of a huge amount of phenolic compounds in them.

Interestingly, not all eucalyptus trees are suitable for koalas. In addition, the animals are very selective in the choice of leaves: they well recognize the presence of hydrocyanic acid in them, which is life-threatening. Moreover, animals are able to estimate its dose. In one night, an adult eats more than 500 g of young shoots and leaves. Special bacteria that develop in the intestines help to cope with this amount of roughage of plant foods.

It is thanks to a special environment that the leaves turn into a nutritious gruel and the proteins necessary for the body are produced. Processed food is stored in cheek pouches, and to speed up digestion, the koala periodically swallows small pebbles and lumps of earth. Sitting on a peculiar diet of leaves saturated with essential oils, the koala is constantly in a state of slight intoxication, which can explain its "inhibition".

Another interesting fact: given that koalas eat, it would be quite natural to assume that the animals drink a lot of liquid. However, this is not the case: koalas practically do not drink water, except for especially hot months. Animals have enough liquid, which they receive with plant food.

Security measures

Due to the fact that most of the traditional habitats of these animals have been destroyed, only scattered populations have survived today. About a hundred years ago, koalas were on the verge of extinction. The people who were attracted to the soft and expensive fur of these animals were to blame for this. In 1924 alone, over two million koala skins were exported from Australia.

Today, koalas are under special protection, their extermination is prohibited. Koalas are bred in zoos and reserves, restoring the population.

reproduction

The decrease in the number of animals is also explained by the low natural increase in the population. Almost 90% of females are sterile, and the rest breed slowly: they devote a lot of time to nursing the cub, which, as a rule, is the only one in the offspring. The mating season for koalas begins in December and ends in March: these months in the southern hemisphere account for the end of spring or the beginning of summer. During this period, the male dominant in a certain area mates with females who are ready to breed.

Mating takes place at night, high up in a tree, and lasts about half an hour. At this time, partners bark, grumble loudly, scratch and bite. After the marriage sacrament, the couple parted, and the male from that moment on forgets about the offspring. After about 35 days, a tiny cub is born, which is completely dependent on the mother. A blind and completely naked baby the size of a bean seed weighs no more than 3 grams. Its hind limbs are not yet formed at the time of birth, and the forepaws with claws are already well developed.

Having been born, the baby crawls into the mother's bag along the path, which the caring female licks in her fur, and for half a year the baby does not leave the bag, tightly attached to the mother's nipple. In the first months, he feeds exclusively on mother's milk, but then the mother begins to feed the baby with gruel from semi-digested leaves excreted with feces.

Six months later, the cub comes out, climbs onto the mother's back and travels with her through the trees. Up to eight months, he periodically hides in a bag, but later it simply ceases to fit in it: you have to put your head in it to refresh yourself with mother's milk. From the age of nine months, the matured animal switches to its own bread. The one-year-old female acquires her own plot, and the adult boyfriend of the mother kicks out the young male during the next mating season.

We answered the main questions of people who are interested in these exotic animals: where does the koala live, what does it look like, how is its life organized. And now we want to present you some interesting facts about these animals.

Koalas cannot be seen in European zoos, as eucalyptus trees do not grow in a temperate climate, and animals are threatened with starvation. Outside of Australia, they can only be seen at the San Diego Zoo, where a eucalyptus forest was planted specifically for these animals.

Now koalas live only in Australia - and even then not everywhere, but only in the southeastern part of the continent. Outwardly, they resemble small bear cubs: inactive with thick short hair of a gray-smoky or reddish color, small round, blind eyes, a flattened oval nose, a short tail and large widely spaced ears with long hair along the edges.

It is now that koalas are one of the symbols of Australia, and once European settlers quickly ousted them from the places of Australia and at the same time almost destroyed their soft fur coat with three centimeters of fur because of the rare beauty. But these animals appeared on the mainland more than 30 million years ago, and according to the beliefs of local aborigines, they were also once people.

How the animal appeared: the version of the natives

The ancient legends of the local natives tell about an orphan boy Kub-Bor (Tashy Bear), who, although raised by his closest relatives, did not like him very much, so they constantly offended him. The boy was taught to survive in the forest and get food. Therefore, he had no problems with food, but it was difficult with water, since Cour-Bor was constantly thirsty.

When one day all the adults went hunting and gathering food, forgetting to hide the buckets of water, a child saw them - and gradually drank all the contents, leaving the tribe without water. After that, he climbed onto a eucalyptus tree and began to sing a monotonous song, from which the tree, on the top of which he was sitting, began to grow extremely rapidly, and by evening it turned out to be the largest in the entire forest. And then the daens (natives) returned.

They did not find water, but found a child hiding in a huge eucalyptus tree. At first they could not reach Cour Bora, because the branches of the huge tree were extremely high. But then two of them managed to climb the tree. The boy was seized by them, beaten right on top of the tree, and thrown down.

Naturally, Kur-Bor crashed to death. But when the natives approached him, they saw that the boy gradually began to turn into a koala. Having completed the transformation, the animal came to life, rushed to the eucalyptus and climbed up.

The last words that the daens heard from the koala were that if he and his kind were killed in order to eat, it would only need to be cooked whole. If anyone disobeys, his spirit will come out of the carcass of the killed beast and severely punish the guilty - such a drought will come that neither people nor animals can survive it. Only koalas will survive, for which the moisture contained in eucalyptus leaves will be quite enough.


The koalas themselves, according to the beliefs of the natives, have not been drinking water since then. Their ancestor, being human, drank plenty of it. This belief arose for one simple reason: before, almost no one had ever seen these animals at a watering place.

Scientists version

It is believed that the koala family appeared more than 30 million years ago, and consisted of at least eighteen species (and some of them were thirty times larger than koalas). As for the "modern" animals, they are much younger. Their age is only 15 million years.

Europeans discovered this animal in the early 19th century. These were the remains of a koala found among the natives. Officer Barralier, who discovered them, alcoholized them and sent them to the Governor of New South Wales. A year later, not far from Sydney, the animal itself was caught.

At first, koalas were found only in the southeast of Australia, as well as in the south of the continent (but they were quickly exterminated there at the beginning of the 20th century in pursuit of profit). It is believed that these animals also lived in the west of the mainland, as evidenced by the remains found there.

Type characteristic

Scientists still have not really been able to determine what kind of animal the animal that lives in Australia belongs to. At first they thought it was a panda or a bear, then they decided that its relative was a wombat, a kangaroo or an opossum (all of them, like the koala, are herbivorous marsupials). But if the relationship still exists, then the researchers have not yet been able to trace their roots.



Animal Features

By itself, the koala is a medium-sized animal. The weight of a large male from the southern part of the continent is about fifteen kilograms, a female from the north is ten kilograms less. The average length of an adult koala is about eighty centimeters.

The marsupial sleeps on trees for about twenty hours a day. Active activity leads at night, climbing on the tops in search of leaves. During the day, even if the animal is awake, it sits motionless or sleeps, hugging the eucalyptus with its paws.


The animal has interesting characteristics that distinguish it from other animals, because of which it was assigned to a separate species.

Paws

The paws of the koala are ideal for climbing trees and allow the adult to grasp tree branches without any problems, and the baby to hold on to the mother's back. The animal sleeps only on eucalyptus, tightly clasping the tree with its paws:

  • The koala has two grasping fingers on its front paws, located slightly apart from the rest;
  • Three other fingers are along the brush;
  • All fingers on the forelimbs have extremely strong claws;
  • The thumb on the foot of the koala does not have a claw (unlike the other four).
  • All koala fingers have fingerprints that are extremely human-like.

Teeth


The teeth of the animal are designed to chew grass. Therefore, their incisors are like a razor and are able to quickly cut leaves. The remaining teeth are grinding, they are separated from the incisors by a wide gap.

Mind and ingenuity

Alas, modern koalas are stupid. If the brain of their ancestors completely filled the cranial cavity, then in animals that have survived to this day, it is much smaller. According to one theory, this happened due to the fact that koalas feed mainly on eucalyptus leaves and shoots, which contain an extremely small level of energy.

Therefore, the brain of modern koalas is only 1.2% of their total weight, and forty percent of the cranial cavity is filled with cerebrospinal fluid. The lack of intelligence negatively affects the life of the animals themselves. For example, accustomed to seek salvation in trees, they do not always consider it necessary to get down from them and run away from the fire. Instead, they only press closer to the eucalyptus trees.

Character

Koala is an extremely calm animal. He sleeps from 18 to 20 hours a day, the rest of the time he devotes to food. The koala lives on a tree, and descends to the ground mainly only in order to move to another eucalyptus, to which it is not able to jump through the air.


From eucalyptus to eucalyptus, they jump extremely easily and confidently. If they decide to flee, they are even able to go to a fairly vigorous gallop to climb the nearest tree.

Nutrition

As for the slowness of the koala not in an emergency, this is primarily due to its nutrition. It feeds only on the shoots and leaves of the eucalyptus tree. The metabolism of the koala is twice as slow as that of other mammals (except for wombats and sloths) - this feature compensates for the insufficient nutritional value of eucalyptus leaves.


The question of why koalas prefer eucalyptus leaves baffles many. Because eucalyptus leaves are not only fibrous and low in protein, but they also contain phenolic and terpene compounds and even hydrocyanic acid, which are extremely poisonous to almost all living organisms.

As for koalas, the deadly poisons that enter the bloodstream from the intestinal tract are completely neutralized by the liver. The animals have a very long caecum - almost two and a half meters (in humans - no more than eight centimeters). It is in it that poisonous food is digested. There are many bacteria in the intestines of koalas that process the leaves into compounds that are digestible for the koala.

On the day the animal eats about one kilogram of leaves, while crushing and chewing them very carefully. And interestingly, the resulting mass is stored in the cheek pouches.

Koalas do not eat leaves from every tree: their extremely good sense of smell allows them to choose only those plants where there are fewer poisonous compounds. Therefore, out of eight hundred species of eucalyptus, koalas eat only one hundred and twenty. And then, when their nose tells them that the food has become too poisonous, they go looking for another suitable eucalyptus for themselves (if the koalas did not have the opportunity to change the tree in time, they often became victims of poisoning).

They give preference to trees that grow on fertile land - they are less poisonous. To compensate for the lack of minerals in the body, animals sometimes eat the earth.

Eucalyptus leaves for koalas are also a source of moisture. They drink water mainly during a drought or when they are sick. In Australia, these animals have recently been increasingly caught near their pools when they come to drink water.

Temperature

Koalas do not have a layer of subcutaneous fat that can protect them from the cold. Firstly, if the temperature is too low, they are rescued by wool (their fur is water-repellent), and secondly, in order to keep warm, their blood circulation, like in humans, slows down.

Communication

Koalas are considered almost the most defenseless and harmless animals in the world. They do not attack anyone and absolutely do not know how to protect themselves. If you hurt them, at best they will run away, most likely they will not hit back and bite.

But this animal can cry. And he can cry as long as the pain causes him discomfort. And the koala cries like a child - loudly, tremblingly and angrily. The same sound can also symbolize the presence of danger.


Koalas are surprisingly silent. Since they live quite far from each other, in order to communicate with their own kind, they use a fairly wide range of sounds.

Males, in order to show their social and physical position, grunt in a peculiar way, and thus find out which of them is cooler (they are not going to waste strength and energy on fights, and if this happens, it is quite rare). Females yell much less often, but sometimes they are able to express aggression with a roar-grunt, and also use this sound to express sexual behavior. But mothers and their cubs do not roar - they make quiet, quiet sounds, reminiscent of clicking (to “talk to each other”) or grumbling (if they are dissatisfied or annoyed with something).


Cries during the mating season

When the mating season begins, the males give such a loud calling sound that it can be heard for a kilometer. Interestingly, this sound is extremely loud and at the same time at a low frequency, which is not typical for small animals the size of a koala. They manage to publish it only with the help of the vocal cords that are behind the larynx.

The female chooses a groom for herself, based precisely on such invocative calls (in any case, preference is given to larger individuals). Despite the fact that the songs of the male remind us of the snoring of a drunkard, the angry grumbling of a pig or the creaking of rusty hinges, females are extremely fond of such sounds and attract them.

The better the koala screams, the more brides he will collect, since there are much more females than males. In one season, one male can have about five wives.

Offspring

Koalas breed once every one to two years. Females create a family already at the age of two, males - at the age of three or four years.

The mother carries the cub for thirty to thirty-five days. Usually only one baby is born, twins are extremely rare. The length of a small koala is from 15 to 18 mm, weight is about five grams, while it is hairless and completely blind. Immediately after birth, the baby climbs into the mother's pouch, where he spends the next six months. So that the cub does not get hurt and does not fall out, the “entrance” to the bag is not located at the top, like a kangaroo, but at the bottom.


At first, he feeds on mother's milk. Weaning from it gradually, and the transitional food is quite original: the mother regularly excretes special stools in the form of liquid porridge from half-digested eucalyptus leaves. The baby needs such food, because this is the only way to get the microflora he needs, since bacteria live in the mother's intestines that help the body cope with food that is indigestible for the child's stomach.

True, such a diet does not last long, after a month he begins to eat the leaves themselves, and at the age of seven months he moves from the bag to his mother's back. Finally, the grown koala leaves the mother's embrace in a year. But far from all leave: while young females go to look for sites for themselves, males quite often stay with their mother for up to three years.


dangers

Usually a koala lives from eight to thirteen years (although in captivity there have been cases when the animals lived to be twenty). Their number for some time (until the Australian authorities took up the solution of this problem) was declining very quickly. If at the beginning of the 20th century the number of koalas was 10 million individuals, then after a hundred of them only 100 thousand remained, most of which live in private territories. In the wild, according to various sources, only from 2 to 8 thousand live.

In nature, koalas have practically no enemies - apparently, the animal soaked in eucalyptus aroma scares off enemies with its smell. Only people eat them, and wild dingo dogs can attack from animals, but this is also a rare occurrence, because koalas rarely go down, and dogs do not jump on trees.


More recently, these animals were on the verge of extinction. The main reason is human activity, as well as their extreme propensity to various diseases.

Diseases

Koalas are rather sickly animals - apparently, the monotonous diet affects. They are especially susceptible to cystitis, periostitis of the skull, conjunctivitis. Sinusitis often causes pneumonia in them, which at the beginning of the last century greatly reduced the population.

They kill animals, and the viral bacteria Chlamydia Psittaci, which are secretly considered the "AIDS" of koalas. They affect the ureter and eyes of animals, and if they are not helped in time, the disease will first lead to infertility, then to vision problems, and eventually to death.

Fur traders

Even before the beginning of the 20th century, a huge number of koalas (more than one million) were destroyed by fur traders, after which there were almost no animals left. And only then (in 1927) the Australian government banned the trade in koala fur, and three years later - to import their skins. This led to the end of the barbaric extermination of koalas, and their population began to gradually increase.

Deforestation

Due to continuous deforestation, koalas are forced to constantly go in search of new trees, so they have to go down. And they are not used to life on earth, because they move here with difficulty, so they become easy prey.


Cars

In connection with deforestation, koalas in search of a new home are increasingly on the tracks. Cars rushing at great speed frighten them extremely, the animals become numb (the so-called "koala syndrome" - males are especially susceptible to it) and stop moving or begin to rush along the road. According to statistics, about 200 koalas are under the wheels of cars every month - and, unfortunately, many of them die in the process.

At the same time, the authorities are trying to solve this problem in a rather interesting way: they stretch artificial lianas over the highway, which connect eucalyptus trees on both sides of the highway. The koalas have appreciated this idea and willingly cross the freeway.

Dogs


Once on the ground and seeing a wild dingo dog, the koala does not understand all the danger, and does not run away to the tree. As a result, it often turns out to be torn apart.

fires

The trees that koalas love to live on contain eucalyptus oil, thanks to which fires flare up extremely strongly and cannot be extinguished for a long time. The fire has completely destroyed more than one population of koalas.

Pools

Many will be surprised to learn how many koalas die when they get into the pool. Contrary to the popular belief that they drink absolutely nothing, they still come to the watering hole, but often not to the source, but to a structure created by human hands, which does not have the usual slopes for animals. Despite the fact that they are excellent swimmers, koalas often drown when exhausted.

Drought

Due to drought, eucalyptus leaves turn black and dry, so koalas deprived of water often die of thirst, especially those who live far from artificial or natural water sources.

animal rescue

If it were for the inactive activities of animal rights activists, we would only know about the koala from the schematic drawings of their textbooks. They managed not only to push through several laws to protect these animals, but also to attract patrons who are ready to donate money to save the "teddy bears".


In Australia, parks and reserves were created, special hospitals were organized for these animals with the latest equipment and highly qualified veterinarians. This is not much, but it helps - about 4 thousand animals are saved a year. Survive about twenty percent of the animals that fell into the hands of doctors.

Life in captivity

As already mentioned, most koalas live in private estates, the owners of which have nothing against such a neighborhood. People are often captivated by the appearance of these cute fluffy animals, similar to teddy bears, and they tame them. Koalas, although they love solitude, they are extremely friendly. They become attached very quickly, and if the person they are used to leaves somewhere, then the animal cries. If you pester them too much, koalas are able to begin to defend themselves with teeth and nails.


Keeping a koala at home is not easy - those who want to get this animal will be required to provide it with at least one kilogram of fresh eucalyptus leaves per day, which is quite difficult. For example, in Russia, these trees grow only in Sochi, but this type of eucalyptus is absolutely not suitable for koalas.

Slow motion world of koalas and sloths

They are in no hurry to go anywhere. As antelopes rush across the savannah, squirrels and weasels flicker among the branches, and kangaroos stomp through the bush, these animals spend their time forever half asleep in the crowns of trees.

Sometimes koalas may seem very nimble. For example, when fighting with dogs or during mating games. At such moments, the Australian "teddy bears", suddenly showing a agility that does not fit with their appearance, look strikingly unusual.


But most of the time they spend at rest, sleeping or sitting completely still, moving only their jaws. The life of koalas is slow and monotonous. Such is the price for the opportunity not to compete with anyone for food resources, eating poisonous eucalyptus leaves.

Eucalyptus leaves are bad food. There is almost no protein in them, they are tough and fibrous, and, worst of all, they have a lot of toxic phenols and terpenes (the main components of resins and essential oils), coumaric and cinnamic acids, and hydrocyanic acid is also present in the petioles of the leaves. But this resource, although low in nutrition, is extremely extensive, because eucalyptus trees, being very unpretentious trees, form forests even where other trees do not survive. It would be strange if such a source of food did not attract any "gastronomic extremes".

Only 120 of the least poisonous of more than 700 species of eucalyptus are suitable for food by koalas, and in order to distinguish edible leaves from others, animals resort to an unusually developed sense of smell. Since all eucalyptus trees belong to the same genus, their smells are very similar, and koalas try to eliminate the slightest mistake.

If you hold leaves edible for koalas in your hands and then offer them to “teddy bears”, they will not eat them: the smell is different from the reference, and the animals will not take risks. There are many cases associated with such “stubbornness” when koalas died in captivity, refusing food, which they definitely ate in freedom, but which for some reason acquired an uncharacteristic smell.

Although the diet of koalas is rich in essential oils, runny noses are not uncommon in these animals: they often suffer from inflammation of the sinuses, from which many die, especially during cold winters. It even reaches the epizootic of respiratory tract infection.


So why is the koala world so slow? Due to the fact that eucalyptus leaves are poisonous, they should not be eaten in large quantities, so that toxins do not accumulate in the body in large quantities. In a day, a koala rarely eats more than half a kilogram of leaves, which is not much for a herbivore weighing more than 10 kilograms. But, since the leaves are not nutritious, they need to be assimilated as best as possible so that nothing useful is lost.

As a result, the koala eats slowly, digests slowly, its entire metabolism is extremely inhibited. The leaves are chewed very carefully, grinding into a gruel, which accumulates in the cheek pouches, where it undergoes primary processing with enzymes contained in saliva.

Then it enters the stomach, and from there to the intestines. Its site, which serves to process coarse fibrous food, is the caecum, part of which has been reduced in our appendix, in koalas it reaches two and a half meters in length. Here, symbiotic bacteria decompose cellulose, which is a long and energy-consuming process. To save energy, the animal sleeps most of the day - 16-20 hours.

What are these marsupial "bears" doing when they are not sleeping? Mostly food, after all, they even drink only in drought or during illness, usually making do with the moisture contained in the leaves. These sweet creatures, alas, are not very interesting to the observer, because, adapting to a low-calorie and toxic diet, they sacrificed a lot, including the size and complexity of the brain, and therefore the complexity of behavior.

The brain is an extremely "expensive" organ in terms of energy, it is not easy to feed it, because it consumes up to 20% of the energy received by the body. Therefore, it is more beneficial for animals to reduce the size of the brain when possible. This even happened to humans: Between 25,000 and 10,000 years ago, our brain shrank by more than 100 cubic centimeters.



In koalas, which, like all marsupials, have never been especially intelligent (marsupials lack a corpus callosum that connects the hemispheres of the brain), the brain has shrunk so much that almost half of their skull is occupied by cerebrospinal fluid. In the brain itself, only the olfactory lobes are well developed, and everything else is tiny. As a result, most of their lives, koalas sit in trees and do nothing at all. They are non-social, silent, they actively communicate with their own kind only during the mating season, when males mark their territory, fight with rivals and assemble a harem of several females.

Mating games take place right on the tree and look very funny. At the end of the breeding season, the harems disintegrate, and the females give birth after a month of pregnancy, as is customary for marsupials, “underdeveloped” cubs, which are carried in a bag for another six months.

In order to digest eucalyptus leaves, a baby koala must acquire the appropriate intestinal microflora, which does not appear by itself. The cubs lick off the mother's excrement, which changes for about a month, turning into a slurry of semi-digested leaves containing cultures of the bacteria necessary for the baby. Growing up, the koala cub leaves its mother and begins to lead an independent life - monotonous and slow, but lasting 15 or even 20 years.

Surprisingly, even after a collision with a person, such a defenseless creature still thrives. Even despite the fact that in the 19th - early 20th centuries, koalas were massively exterminated by hunters (and hunting animals that are not afraid of anyone, do not run away and do not hide, is as easy as shelling pears), harvesting up to two million skins a year, until 1927 th, when hunting for them was prohibited. Of course, in the modern world of these animals, many dangers await. For example, ticks accidentally imported from Japan.



And when, during the mating season, koalas descend from trees and actively move along the ground, they risk being hit by a car while crossing the highway or catch the eye of dogs who will not miss the opportunity to hunt such an animal. Even though koala meat is completely inedible, which reliably protected it from local predators. Many enthusiasts are involved in rescuing wounded koalas, who deliver them to special centers or to ordinary veterinary clinics.

The closest relatives of koalas, wombats, also have a slow metabolism, but live on the ground and are less picky about food.

THE LAZY MASTER OF SYMBIOSIS

Much north of koalas, in South America, live creatures with an equally slow metabolism. These are two-toed and three-toed sloths. Living in an environment of numerous predators, not constrained by a strict diet, they nevertheless preferred non-action, glorified by the Taoists. The lifestyle of sloths is in many ways similar to that of koalas. For more than half of the day, sloths sleep, completely relaxed, hanging on the branches of trees, on which they are held with the help of long curved claws, outwardly (and functionally) similar to the “claws” of assemblers and rural electricians.



It is amazing that the “hang and don’t shine” strategy has allowed sloths, which feed on both jaguars and harpy hawks and other hunters of seemingly easy prey, to multiply so much that in some areas of their habitat the sloth biomass is two-thirds of the total biomass. mammals. There are sometimes over 750 sloths in one square kilometer of the rainforest. This is an incredible density for large mammals! Animals hang motionless in the crowns of trees, merging in color with foliage, and predators simply do not notice them.

Sloths have four times less skeletal muscle than other mammals of the same size. This is both a plus - less energy is spent on maintaining muscles, - and a minus: once on the ground, "weak" sloths can neither offer real resistance to anyone (although sometimes they scare away enemies, hissing and waving their long clawed paws), nor escape , especially since they are not able to walk normally and step on the outer part of the claws.



Once upon a time, sloths were a thriving family, most of whose members were diurnal (as opposed to the current ones, active at night) and highly mobile animals. Megatheria, the ancestors of modern sloths, were three meters tall and weighed half a ton. However, everyone died out, except for those who made secrecy and physical inactivity a survival strategy.

The adaptation of sloths to a sedentary hanging lifestyle has affected their entire anatomy and physiology. Their brain, like that of koalas, is relatively small (although much larger: after all, sloths are placental mammals, not marsupials), the convolutions are strongly smoothed, only the olfactory parts of the brain are well developed.

Like koalas, sloths do not drink water, but are content to lick off the dew. The internal organs are displaced, for example, the liver is adjacent to the back. Unlike all other mammals, sloths do not necessarily have seven cervical vertebrae, but can reach up to nine. A large number of cervical vertebrae will give the animal the ability to cut foliage over a larger area, moving only its head.

The body temperature of sloths is unstable, on cool nights they cool down to 12 ° C, and on a hot day they can heat up to 35 ° C without harm to health. Sometimes they gather in groups for warmth and hang, clinging to each other. In the same place, as it is believed, they mate. Unlike koalas, sloths eat a variety of plants, not only foliage, but also buds, flowers, and young shoots.

Like most herbivores, they do not refuse protein food if they are lucky to eat insects or lizards. And in times of famine, they can even eat algae that live in their wool.

Blue-green photosynthetic algae are normal, of course, not a food supply, but camouflage. The greenish coat that grows in sloths not from front to back, but vice versa (that is, by stroking the animal with the usual movement from head to tail, you stroke it against the coat), perfectly camouflages the animal, making it almost invisible in the crown of the tree. In addition to algae, they have other symbionts. The sloth, like the koala, cohabitates mutually with abundant intestinal flora.




And in his wool (and only there) moth butterflies settle Bradipodicola hahneli. Adult insects feed on algae, and the larvae develop in the excrement of sloths. For reasons that are not entirely clear, these animals defecate only on the ground, where they descend about once a week (they have a huge bladder). For excrement, the sloth digs a hole at the roots of the tree on which it lives, and fertilizes it with its feces, thus entering into a kind of symbiosis with the tree. It is a pity that the number of these mammals is declining. This happens due to the reduction of tropical forests, in which sloths feel at ease, but outside of their limits they cannot exist.

Alas, sloths also have such cohabitants, without whom both they themselves and we, people, could well do without. These are protozoa, the causative agents of leishmaniasis, a dangerous disease.

Why, if both sloths, which live up to 30 years (longer than other mammals in the same places), and koalas thrive in their slow world, almost no one followed suit? Why do other mammals prefer to be swift and agile, despite the high "energy price" of an active lifestyle? In order to allow yourself to live slowly, with atrophied muscles and a weak brain, you need to get into a very unusual situation. One where giving up the desire for speed would be beneficial.



For example, it will provide an opportunity to develop a food base that no one needs, without risking becoming someone's prey, or, using symbiosis with algae, to hide from predators who cannot notice the motionless green beast in the foliage. Such lucky coincidences are probably extremely rare, and those who tried to get out of the “race for speed” without such favorable initial prerequisites disappeared without leaving descendants.

Journal January 2013

The marsupial bear is one of Australia's most famous animals. Despite the outward resemblance to ordinary bears, this representative of the Australian fauna has nothing to do with them. The eucalyptus bear is found only in certain parts of Australia and few people have the opportunity to see this miracle of nature with their own eyes.

The marsupial bear is one of Australia's most famous animals.

Not every zoo can provide these animals with the amount of eucalyptus leaves they need. Koalas require special attention from humans, as they are an endangered species. Their numbers were raised only recently, when measures were taken to ban hunting and protect the eucalyptus forests that serve as a home for these amazing creatures.

What do we know about marsupial bears (video)

The history of the development of the species

The marsupial bear is a two-pronged marsupial that is the only living member of the koala family. The modern eucalyptus bear is a small animal. The weight of adults varies from 5 to 14 kg. Females are usually smaller than males. In these animals, in the process of evolution, the body was ideally adapted for life on a tree and eating low-nutrient foliage. For a long time, these creatures were attributed to kinship with pandas, kangaroos and opossums, but this is not true.

Archaeological excavations in different parts of Australia have helped to lift the veil of the mystery of the appearance of the koala bear. Thanks to the fossilized remains, it became known that the first marsupial bears began to appear in this area about 30 million years ago. In those distant times, more than 18 species of koalas lived on this remote continent, and some of them were real and giants. They were 30 times larger than their contemporaries.

It is believed that the giant marsupials died out due to climate change becoming excessively arid, as the eucalyptus trees and some other plant species that they bypass began to rapidly disappear.

During this period, many marsupials died out, which successfully survived in the vastness of this continent for millions of years. Plush-looking modern koalas appeared in Australia only 15 million years ago. This species was the most successful, so it outlived its relatives. Koalas of Australia, unlike their ancient relatives, are distinguished by a relatively small brain. Scientists attribute this to the fact that animals eat low-calorie eucalyptus leaves and lead an inactive lifestyle, so they simply do not need a developed brain.

The marsupial bear is a two-pronged marsupial animal, which is the only living member of the koala family.

These creatures have beautiful deep gray fur, making them hard to spot in the foliage. They were first described in the 19th century, when there was an active development of a new continent. Because of their beautiful warm coat, by the beginning of the 20th century, koalas were almost universally exterminated. Their fur for a long time was perhaps the most valuable export product of Australia, which had an extremely negative impact on this species. In addition, their numbers were negatively affected by the widespread destruction of eucalyptus forests.

Among other things, an attractive appearance and gentle disposition led to the fact that many people in the 20th century wanted to acquire such a pet. However, keeping a koala at home is almost impossible. These marsupial herbivores consume only the leaves of certain types of eucalyptus trees, so when trying to keep them at home, the animals, as a rule, quickly died from exhaustion.

Gallery: marsupial bear (25 photos)








Habitat of koalas in nature

The natural habitat of the koala bear is extremely limited. These amazing creatures are found mainly in coastal areas in the east and south of Australia. There is a small population of koalas in the north of the continent. In addition, koala bears are currently found on a number of offshore islands, where optimal conditions have been created for them.

Koalas feed exclusively on eucalyptus leaves, so their habitat is limited to humid tropical and subtropical forests, in which there are many trees that can become a food base for them.

The koala tree - eucalyptus - can only grow in regions with high humidity, so only in certain regions can these animals thrive, which causes them to conflict with human interests. There are several types of eucalyptus trees that animals feed on at different times of the year. This is no coincidence. The leaves of certain species of eucalyptus are distinguished only for a short period by a reduced amount of hydrocyanic acid.

Despite the fact that the koala bear can smell the degree of poisonous foliage by smell, poisoning in these animals is not uncommon.

Plush-looking modern koalas appeared in Australia only 15 million years ago

In addition, it is known that out of almost 800 species of eucalyptus, only 120 species can feed on the leaves and bark of the koala. Vast areas of forests in southeast Australia were cut down in the 20th century, which adversely affected the life of the koala. To increase their numbers, these animals were brought to a number of coastal islands with dense eucalyptus forests, where marsupials are less subject to anthropogenic influence, which allows them to gradually increase their numbers.

The islands where koalas have been settled by humans include:

  • Yanchep;
  • Kangaroo;
  • Tasmania;
  • Magnetic island.

Thanks to conservation measures, the habitat of this species currently exceeds 1 million / m². Despite the fact that even in the middle of the 20th century these unique animals could have become extinct, now their numbers are gradually recovering.

Koala in the wild in Australia (video)

Reproduction and habits of koalas

The Australian eucalyptus bear leads a hidden lifestyle, so little was known about their behavior for a long time. These creatures are covered with thick fur 3 cm long, which makes them invisible in the foliage. During the day they eat about 1.5 kg of young leaves and bark of eucalyptus trees. Approximately 18-20 hours a day, these creatures sleep. It is currently unknown how long koalas live in their natural habitat.

In captivity, when creating optimal conditions, koalas often live up to 18 years. In their natural habitat, koalas have no enemies, so they do not know how to defend themselves. Despite the fact that koalas have long claws and strong prehensile paws designed for climbing trees, when attacked, these animals simply do not know what to do. When severely frightened or injured, the koala makes a sound similar to the crying of a human child. In addition, koalas can cry.

For most of the year, koala bears are extremely silent and try not to give out their location in the thickets of eucalyptus, but everything changes during the breeding season. At this time, the males begin to make inviting grunting sounds, demonstrating their strength. Considering that colas usually live nearby, since their habitat is quite limited, this method is very effective. Koala females are ready for breeding as early as their second year of life. Mating occurs 1-2 times a year. Males can mate at 3-4 years of age. During the breeding season, male koalas can engage in fights, inflicting serious injuries on rivals with their claws.

Females ready for mating listen to the calls of roaring males and choose the largest representatives. Pregnancy in female koalas lasts from 30 to 35 days. Koala cubs are born very underdeveloped, so they can look very strange by human standards.

After the birth, the bear cub, which has only developed front legs, clings to the mother's thick fur, crawls into the bag, where it begins to feed on milk. At this time, its weight is about 5 g, and the length varies between 15-18 mm.

Koala bears are marsupials. Their offspring are fed in a bag for 5-6 months. After the calf leaves the pouch, it continues to travel on its mother's back for about 6 months. Thus, a koala with a cub is a common occurrence. At this time there is a transitional period.

The mother begins to feed the cub with undigested litter from eucalyptus leaves, which contains the bacteria necessary for the bear cub, which are involved in digestion. Usually females stay with their mother for about a year, after which they begin to search for their own territory. Males can stay with their mother for about two years, as they lead a predominantly nomadic lifestyle and are not tied to a specific area.

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