Tardigrades are microscopic invertebrates related to arthropods, ranging in size from 0.1 to 1.5 millimeters.

They were first described in 1773 by the German pastor and researcher Johann August Goetze. He called this creature "little water bear" (German kleiner Wasserbär), although not every observer will find the resemblance obvious. The translucent body of the tardigrade consists of four segments and a head. She has four pairs of short thick legs, each of which ends in a claw. They move very slowly: 2-3 mm/min. Actually, therefore, in 1777, the Italian scientist Lazzaro Spallanzani called them tardigrades.

In the mouth they have several sharp teeth-needles, with which they bite into plants or animal prey. Large tardigrades can eat rotifers, nematodes and even other tardigrades. Due to their phenomenal vitality, they are distributed throughout the planet from the mountain peaks of the Himalayas to sea ​​depths. They are carried by wind, water and animals. Most of all they love freshwater ponds and wet lichens.

For normal life, all living organisms need a number of conditions of approximately the same level: average temperature from -10 to +35 degrees, the presence of water in a liquid state and the absence of external harmful effects, radiation for example. A critical (i.e., sharp and large) change in these conditions for most living beings will mean death. But there is an animal on Earth that literally destroys all our ideas about life and the limits in which it can exist.

This animal - . The tardigrade is a microscopic animal that looks like a tiny bear, which is probably why they were called "little water bears" by their discoverer, the German I. Getze. Their body length can range from 0.1 to 1.5 millimeters, depending on the species. Speaking of species, more than 900 species of tardigrades are now known to be found around the world in a wide variety of places and conditions. Most tardigrades are terrestrial species, but some species prefer the water element and inhabit both small fresh water bodies and the seas and oceans.

Tardigrade recognized the hardiest creature on earth, no other creature is able to survive in the conditions in which the tardigrade can survive. This tiny animal can easily withstand extremely high and extremely low temperatures, ultra-high pressure, complete absence moisture, lack of air and vacuum, as well as huge doses of radiation.

To be more specific, tardigrades survive at temperatures from +190 before -279 degrees Celsius, moreover, they are not only able to survive in such extreme conditions, for some species such temperatures are the norm (for tardigrades living near underwater thermal springs a temperature of 110-120 degrees is quite familiar).

As for the drought, here the "water bears" distinguished themselves even more noticeably - with a long absence of water, they are able to fall into anabiosis(cessation or a very strong slowdown of all processes in the body, the so-called imaginary death). During suspended animation, their body decreases in size and is covered with something similar to wax in order to retain the smallest traces of moisture. Anabiosis can last up to 2 years, and in order to come to life, only a drop of water will be enough.

this is what a tardigrade looks like in a state of suspended animation

A number of experiments by Japanese scientists have confirmed other incredible abilities of tardigrades: - able to withstand maximum pressure 600 MPa (for example, at the bottom of the Martian Trench, under an 11-kilometer layer of water, the pressure is 100 MPa); - transfer the level of radiation to 10 times more than any other animal.

Boil it, put it in a pressure chamber for several hours, then freeze it, completely dehydrate it, and finally, expose it to radioactive radiation. No, this is not a gourmet recipe. All these actions are united by the fact that they can easily be transferred by the most tenacious creature on the planet - the tardigrade.

So imagine the following experiments:

  • freezing with liquid helium to -271 C for eight hours, and then more than a year of existence at a temperature of -173 C;
  • exposure to radiation of 500,000 roentgens (for comparison, only 500 roentgens are enough to kill a person);
  • completely deprive for several days of oxygen;
  • put in a pressure chamber with a pressure of 6000 atmospheres (in the ocean at a depth of 1 km, the pressure is about 100 atmospheres);
  • lift into outer space ();
  • deprive of water for a hundred years;

If a tardigrade would offer to an ignorant person to bet that after all these unpleasant procedures she would survive, then the cunning invertebrate would easily win!

Tardigrades can withstand such doses of radiation fifty times higher than the doses withstand famous cockroaches. And they are the only living creatures that, without consequences, can for a long time stay in the near-vacuum space. In dry climates, a tardigrade can remain dormant for more than 100 years, and then wake up when the environment is wet enough. During the experiment, it was found that some individuals came to life after 120 years of conservation!

Tardigrades have been known to science since 1770 and many of their species have been discovered to this day, living in the most extreme places on the planet. Tardigrades have been found under arctic cap ice, in deserts where there has been no rain for several decades, in geothermal springs, where the temperature exceeds the limits that seem to be possible for living beings.

On this moment about 900 species are known, 120 of which live in Russia. You may even be able to spot a few record holders in a country pond or in the moss of trees. Fortunately, some species can be distinguished with the naked eye, as their body grows up to 1.5 mm.

What allows the tardigrade to endure so many extreme conditions? She owes this to her unique feature of almost completely turning off metabolism and hibernating. At the same time, the tardigrade actively produces a substance called trehalose, a disaccharide that protects the membranes that make up the creature's body. By the way, scientists seriously consider trehalose as one of the components that will help to avoid cellular damage during freezing in a cryochamber. After falling asleep, the tardigrade loses up to 97% of its body weight and can be easily carried even by air currents, traveling high above the surface.

The combination of these factors makes it possible to assume who will be the new owner of the Earth in the event of a global catastrophe.

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The Sahara is the largest and driest desert on the planet. The inhabitants of the Sahara fight daily for their survival. Only the most enduring creatures can survive here.

About a quarter of the desert is covered with sands, which are practically lifeless. These sands formed on the plains eroded by the rivers. The rest of the Sahara is a pebbly desert, which is flat hills and plateaus.

The Sahara is the queen of the deserts.

Today's relief of the Sahara was formed under the influence of precipitation, which in ancient times was very plentiful. Rains still change the landscape of the desert today, but most of the modifications are due to the movement of sand. The sand, moving slowly, polishes the rocks to a shine, makes depressions in them, and drills through some. In this regard, the relief of the Sahara desert is constantly changing.

The eastern part of the desert is one of the sunniest places on the planet. The sun's rays warm it for 4 thousand hours a year, that is, about 11 hours a day.


The most poisonous fat-tailed scorpion on the planet lives in this desert. If he bites a person, then he will die after 4 hours, and a bitten dog dies in a few minutes.

When it blows in the Sahara strong wind, then sand particles rise into the air, which reach the very Alps. In this case, the snow in the mountains turns red.


The finch is a resident of oases in the Sahara.

The most heat on our planet was observed in the Libyan city of El Aziziya, it was +58 degrees in the shade.

The area of ​​the desert is 9 million square kilometers. It is located in North Africa and covers an area from Atlantic Ocean to the Red Sea. The Sahara is almost the size of the United States.

Birds living in the Sahara


Most birds feed on insects, but also live in the Sahara predator birds such as ravens and falcons. Larks and try to stay close to the oases. And hazel grouse settle in the desert, and for water they have to fly long distances. When the male drinks water, the feathers on his chest are also saturated with liquid, and then the chicks drink it.

Climate and vegetation of the Sahara

In most of the desert, not even a hundred milliliters of precipitation falls per year (in comparison, in Central Europe, the annual rainfall is about 1000 milliliters). And in certain parts of the Sahara there is no rain for several years, only a sudden change in the weather brings long-awaited moisture. For animals living in the Sahara, the only source of water is the dew that has fallen in the morning.


The ship of the desert is a camel.

During the day in the Sahara, unbearable heat, but at night it gets cold. There are two groups of plants growing in the desert. The first group includes vegetation with small leaves and a branched root system. And the second group includes plants - ephemera, which give seeds that can lie in the soil for several years until the long-awaited moisture arrives. As soon as it will rain, such plants give offshoots, they instantly grow and bear fruit. Such growth occurs very quickly, in just a couple of weeks. But date palms also grow in the Sahara, which cannot be attributed to any of these groups.

World of insects, reptiles and amphibians

Insects, spiders and scorpions of the Sahara get their moisture mostly from food. As a rule, the bodies of these creatures are covered with a chitinous shell, which does not allow fluid to quickly leave the body. Among other things, many insects secrete a special wax from their bodies, which creates a protective film on the body.


Some insects, for example, with the advent of rain, begin to multiply rapidly.

Snakes and lizards feed on insects and other invertebrates, obtaining from them required amount moisture. On cold nights, many reptiles have to fall into a state of torpor, in which blood circulation slows down. And in the morning, warmed by the sun, they go in search of food.

The air temperature during the day is very high, so some lizards have to hide from the heat underground. Snakes, for example, horned vipers, burrow deep into the sand, because at depth it is cool and wet.


Dorcas are gazelles that live in the Sahara.

Amphibians need water to reproduce. Frogs living in the Sahara, in the absence of water bodies, lay their eggs only after rain in small puddles.

Mammals living in the Sahara

Many mammals would not be able to withstand the harsh conditions of the desert, they would soon die of heat stroke and dehydration. But swift-footed gazelles have adapted to life in the Sahara. It is worth noting that they do not just have to, for example, Gazelle-Dorcas has been in search of plants all his life, from which you can get at least not a large number of moisture.

Addax also gets moisture from food. They have spiral-shaped black horns and wide hooves that allow them to move across the sand with ease. Oryxes used to live almost throughout the entire Sahara, but people began to exterminate them en masse, significantly reducing their number. The dromedary, or "ship of the desert", or the one-humped camel is adapted to life even in the most difficult climate. He has two long fingers on each foot, they have pads that allow the camel to walk calmly on hot sand.

Most of the mammals living in the Sahara Desert are small in size. Typical inhabitants of the desert are Gunde, similar to guinea pigs, and Fenech - small foxes with huge ears.

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They survive up to ten years without water, are able to survive at -271°C in liquid helium and at +100°C in boiling water, withstand 1000 times the dose of radiation than humans, and have even been to open space!

Tardigrade (lat. Tardigrada) is a type of microscopic invertebrates close to arthropods. This animal was first described in 1773 by the German pastor J. A. Götze as kleiner Wasserbär (small water bear). In 1777, the Italian scientist Lazzaro Spallanzani gave them the name il tardigrado, the tardigrada, the Latinized form of which is the name Tardigrada (since 1840).

The body of tardigrades (or they are also called a water bear) has a size of 0.1-1.5 mm, translucent, of four segments and a head. Equipped with 4 pairs of short and thick legs with 4-8 long bristle-like claws at the end, with the last pair of legs directed backwards. Tardigrades move really very slowly - at a speed of only 2-3 mm per minute. Mouth organs are a pair of sharp stylets used to pierce the cell membranes of algae and mosses, which tardigrades feed on. Tardigrades have digestive, excretory, nervous and reproductive systems; however, they lack the respiratory and circulatory systems - skin breathing, and the role of blood is performed by the fluid filling the body cavity.

Currently, more than 900 species of tardigrades are known (in Russia - 120 species.). Due to their microscopic size and ability to endure adverse conditions, they are ubiquitous, from the Himalayas (up to 6000 m) to the sea depths (below 4000 m). Tardigrades have been found in hot springs, under ice (for example, on Svalbard) and on the ocean floor. They spread passively - by wind, water, various animals.



All tardigrades are aquatic to some extent. Approximately 10% - Marine life, others are found in freshwater reservoirs, but most inhabit moss and lichen cushions on the ground, trees, rocks and stone walls. The number of tardigrades in moss can be very large - hundreds, even thousands of individuals in 1 g of dried moss. Tardigrades feed on liquids of plants and algae on which they live. Some species eat small animals - rotifers, nematodes, and other tardigrades. In turn, they serve as prey for ticks and springtails.

Tardigrades attracted the attention of the first researchers with their amazing endurance. On the onset adverse conditions they are capable of falling into a state of suspended animation for years; and with the onset of favorable conditions, it quickly revives. Tardigrades survive mainly due to the so-called. anhydrobiosis, drying.



When dried, they draw limbs into the body, decrease in volume and take the shape of a barrel. The surface is covered with a wax coating that prevents evaporation. During anabiosis, their metabolism drops to 0.01%, and the water content can reach up to 1% of normal.

In a state of suspended animation, tardigrades endure incredible loads.

* Temperature. Withstand stay for 20 months. in liquid air at -193°C, eight hours of liquid helium cooling down to -271°C; heating up to 60-65°C for 10 hours and up to 100°C for an hour.

* Ionizing radiation of 570,000 roentgens kills approximately 50% of exposed tardigrades. For humans, the lethal dose of radiation is only 500 roentgens.

* Atmosphere: Revived after half an hour in a vacuum. Quite a long time can be in the atmosphere of hydrogen sulfide, carbon dioxide.

* Pressure: In an experiment by Japanese biophysicists, "sleeping" tardigrades were placed in a sealed plastic container and immersed in a chamber filled with water high pressure, gradually bringing it to 600 MPa (approx. 6000 atmospheres), which is almost 6 times higher than the pressure level at the lowest point Mariana Trench. It does not matter what liquid the container was filled with: water or a non-toxic weak solvent, perfluorocarbon C8F18, the survival results were the same.

* Humidity: a case is known when moss taken from the desert after about 120 years after its drying was placed in water, the tardigrades that were in it came to life and were able to reproduce.

In September 2007, the European Space Agency sent several specimens into space to a height of 160 miles. Some water bears were only exposed to vacuum, some were also exposed to radiation, 1000 times higher than the Earth's background radiation. All tardigrades not only survived, but also laid eggs, successfully breeding.

Experiments in orbit have shown that tardigrades - tiny arthropods ranging in size from 0.1 to 1.5 millimeters - are capable of surviving in outer space. In their work, the results of which are published in the journal Current Biology, biologists from several countries have shown that some tardigrades are able to fully restore their vital functions and produce viable offspring.

In this work, a team of biologists led by Ingemar Jonsson of the University of Kristianstad sent two species of tardigrades, Richtersius coronifer and Milnesium tardigradum, into Earth's orbit. The arthropods spent 10 days aboard the Russian unmanned aerial vehicle Photon-M3. A total of 120 tardigrades have been in space, 60 of each species. During the flight, one group of arthropods, including both species, was in a vacuum (a shutter was opened separating the chamber with tardigrades from outer space), but was protected from solar radiation special screen. Two more groups of tardigrades spent 10 days in a vacuum and were exposed to ultraviolet A (wavelength 400 - 315 nanometers) or ultraviolet B (wavelength 315 - 280 nanometers). The last group of arthropods experienced all the "features" outer space.

All tardigrades were in a state of suspended animation. After 10 days spent in outer space, almost all organisms were dried up, but on board spacecraft tardigrades returned to normal. Most of the animals exposed to ultraviolet radiation with a wavelength of 280 - 400 nm survived and were able to reproduce. R. coronifer specimens failed to survive the full range of exposures ( low temperature, vacuum, ultraviolet A and B), only 12% of the animals of this group survived, all of them belonged to the species Milnesium tardigradum. However, the survivors were able to produce normal offspring, although their fertility was lower than that of the control group that was on Earth.


So far, scientists do not know the mechanisms that helped tardigrades survive exposure to the harsh ultraviolet radiation of outer space. Radiation of this wavelength causes breaks and mutations in DNA. Possibly, tardigrades have special defense systems that protect or quickly repair their genetic material. Understanding how living systems are able to protect themselves from the destructive effects of space is important for the development of astronautics and the organization of space flights over long distances and a lunar base.


What is the secret of such survivability of tardigrades? They are not only able to reach a state where their metabolism practically stops, but also to maintain this state for years at any time during their existence.

Here is an example of an arctic Adorybiotus coronifer frozen like this:

But the seasonal changes of this creature depending on weather conditions (1 - cold autumn and winter; 2 - spring; 3 – active form, summer; 4 - molt):

Thus, the existence of tardigrades refutes the theory that only cockroaches can survive nuclear explosion. This creature is much more tenacious, many times smaller than a cockroach, and also much cuter :)


Their Italian name "tardigrado" is of Latin origin and means "slow moving". It was given at the discovery of animals due to their slow movement. Tardigrades are almost transparent and on average reach half a millimeter in length. The body of the tardigrade consists of five parts: a distinct head with a mouth and four segments, each of which has a pair of legs with claws. The body of animals is covered with a thin and flexible cuticle that is resistant to impact, which they shed as they grow (molt). Anatomical structure these small animals resemble the structure of larger ones. In particular, tardigrades have a brain on the dorsal side, small eyes, and ganglions on the ventral side (like those of flies). Their digestive system includes a mouth with sharp stylets and a sucking expansion of the pharynx for sucking out the contents of the cells of other microscopic animals or plants, intestines and anus. Fortunately, tardigrades are not pathogenic to humans. They have longitudinal muscles and excretory organs.


A single sac-like gonad located dorsally distinguishes males, females, and self-fertilizing hermaphrodites. Some species consist only of females that reproduce by parthenogenesis, that is, without the participation of males. Due to their small size, tardigrades do not require respiratory and circulatory systems for gas exchange. The fluid present in the body cavity performs the functions of the respiratory and circulatory systems. Systematically, tardigrades are very close to arthropods, in particular, to crustaceans and insects, which also lose their cuticle in the process of growth and have the largest number of species on Earth. Being very close to arthropods, tardigrades are not. Various species of tardigrades have been found everywhere on the planet: from the polar regions to the equator, from coastal zones1 to the depths of the ocean, and even on the tops of mountains. To date, approximately 1,100 species of tardigrades have been described that live in the seas, lakes and rivers or in ground environment a habitat. Their number is rapidly increasing every year due to new discoveries and revisions of existing species.

Although all tardigrades need water to survive, many species can survive even with a temporary lack of water. Thus, the largest number of tardigrades was found on the ground, where they live in mosses, lichens, leaves and moist soil. The wide distribution of tardigrades on Earth is closely related to their survival strategies.

Terrestrial tardigrades can live in two main states: active and cryptobiosis2. When active, tardigrades need water to eat, grow, reproduce, move, and carry out normal activities. In the state of cryptobiosis, metabolic activity stops due to lack of water. When conditions change environment and the appearance of water, they can again return to active state. This reversible suspension of metabolic activity has naturally been compared to death and resurrection. Terrestrial tardigrades respond to stimuli differently depending on the stressors, and their responses are collectively referred to as cryptobiosis. This condition can be caused by desiccation (anhydrobiosis), freezing (cryobiosis), lack of oxygen (anoxibiosis), and high concentrations of solutes (osmobiosis).

Anhydrobiosis, a state of metabolic dormancy due to near-total desiccation, is common in terrestrial tardigrades, which may enter this state several times. To survive in this transitional state, tardigrades must dry out very slowly. Grass, mosses and lichens inhabited by terrestrial tardigrades contain numerous accumulations of water, like sponges, which dry out extremely slowly. Tardigrades dry out as their environment loses water. They have no other way to escape, because tardigrades are too small to run. The tardigrade loses up to 97% of its water content and dries out to form a shape roughly equal to one-third of its original size, called a "barrel". The formation of such a "barrel" occurs as the animal draws its legs and head into the body to reduce its area. When rehydrated by dew, rain or melting snow, the tardigrade can return to an active state in a few minutes or hours. This amazing ability to survive, apparently, is a direct reaction to the rapid and unpredictable changes in the terrestrial microenvironment.

Marine tardigrades do not develop such features as their environments tend to be more stable. An animal can be in a state of anhydrobiosis from several months to twenty years, depending on the species, and survive almost everything. The most well-known feature of the tardigrade is the ability to survive in extremely extreme conditions. During the experiments, dehydrated tardigrades were exposed to temperatures ranging from minus 272.95°C, i.e. close to absolute zero, up to +150°C, i.e. temperature in the oven when baking a cake. After rehydration, the animals return to an active state. Thus, tardigrades that were in a state of anhydrobiosis for several years at a temperature of -80°C survived. Tardigrades have also been exposed atmospheric pressure, 12,000 times greater than normal pressure, as well as exposure to excessive amounts of asphyxiating gases (carbon monoxide, carbon dioxide), and they managed to return to an active state after rehydration. Exposure to ionizing radiation, more than 1,000 times fatal to humans, had no effect on tardigrades.

In 2007, the tardigrade became the first animal to survive the harsh environment of space. During an experiment carried out in the TARDIS spacecraft, thanks to equipment provided by the European Space Agency, tardigrades in a state of anhydrobiosis were directly exposed to solar radiation and space vacuum during the mission of the Russian spacecraft "Photon-M3". During the movement of the apparatus in orbit at a distance of 260 km above the Earth's surface, scientists opened a container in which there were "barrel" tardigrades, thereby exposing them to the sun and, in particular, ultraviolet radiation. Upon returning to Earth after rehydration, the animals began to move - they survived.


In the summer of 2011, during the TARDIKISS experiment, supported by the Italian Space Agency, tardigrades were sent into space to the International space station(ISS) on space shuttle NASA Endeavor. Tardigrades and their eggs have been exposed to ionizing radiation and microgravity. And again, after the return of the animals to Earth, the individuals hatched from the eggs and the animals survived: they ate, grew, molted and multiplied, as if they had returned from a pleasant little cruise through space. What biological resistance mechanisms do tardigrades use to protect themselves under these various stressful conditions?

The physiological and biochemical mechanisms of tardigrades that ensure the endurance of tardigrades are still little known, and to date there is no generally accepted explanation. However, in the past few years, the endurance of tardigrades has attracted the interest of a large number of scientists who have applied new molecular and biochemical tools in their research. It is now clear that the mechanisms underlying anhydrobiosis may contribute to the endurance of tardigrades under other stressful conditions, using different biochemical and physiological mechanisms. The underlying mechanism involves the synthesis of various molecules that act together as bioprotectors: trehalose, sugar, and stress proteins commonly referred to as "heat shock proteins".

With dehydration, the loss of a significant amount of water, as a rule, leads to the destruction of cells and tissues and, consequently, the death of the organism. In the case of tardigrades, there is a relationship between the acquisition of resistance to dehydration and the biosynthesis of trehalose as this sugar accumulates in tardigrades when dehydrated. The synthesis and accumulation of trehalose protects the cells and tissues of the tardigrade by replacing the water lost during dehydration. Heat shock proteins, in particular the HSP70 protein, likely act in concert with trehalose to protect large molecules and cell membranes from damage caused by dehydration. Ionizing and ultraviolet radiation destroy large molecules such as DNA and lead to oxidative stress, producing an effect similar to accelerated aging.

It is for this reason that the ability of tardigrades to survive intense radiation leads scientists to the idea that animals have an effective DNA repair mechanism and a protective system of antioxidant action. The growing interest of scientists in tardigrades is undoubtedly associated with the possibility of applying the knowledge gained about dehydration and the mechanisms of frost resistance of tardigrades to the cryopreservation of biomaterials (for example, cells, vaccines, food, etc.). These tiny, invisible animals can help us understand the fundamental principles of the nature of living systems. So be careful when walking on the grass.