Anabiosis (from Lat. Anabiosis - "revitalization") is a state of a living organism, in which life processes (metabolism, etc.) are so slowed down that all visible manifestations of life are absent. At least, such a definition of this term is given by the Biological Encyclopedic Dictionary.
Rotifer
Anabiosis is a widespread phenomenon in the animal kingdom. For example, in insects at subzero temperatures, their entire development slows down or practically stops. Bats, rodents, some birds, reptiles, and amphibians can plunge into torpor.
For the first time, back in 1705, the Dutch inventor of the microscope Anthony van Leeuwenhoek drew attention to the phenomenon of suspended animation. And this happened after he took dry sand, moistened it and placed it under the eyepiece of the microscope. To Levenguk's surprise, the motionless creatures began to move. These were microscopic worms - rotifers.
In 1743, the English naturalist John Thurberville Needham observed a similar phenomenon in the wheat nematode Tylenchus Tritici. The larvae of this worm could survive for at least two years in dried wheat grains. Once in the soil together with the grains, the nematode larvae "revived".
In 1777, the Italian scientist Lazzaro not only confirmed Levenguk's experiments on rotifers, but also discovered tardigrades - microscopic creatures that live in mosses and lichens. It turned out that tardigrades, like rotifers, endure prolonged drying and come to life after being moistened.
Over time, several points of view have appeared on the factors that allow organisms to tolerate prolonged drying. So, Leeuwenhoek assumed that rotifers are protected from drying out by a dense membrane that retains moisture. In turn, T. Needham believed that dried rotifers maintain life without water and oxygen due to some peculiarities of their organism.
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Decades passed, but interest in the “phenomenon of resurrection” of animals and plants did not wane, but, on the contrary, attracted more and more attention. Finally, in 1873, the German scientist Wilhelm Preyer proposed to call this amazing phenomenon suspended animation.
Numerous studies of suspended animation in animals were carried out by the Russian scientist P. I. Bakhmetyev. He studied the effect of low temperatures on the physiology of insects and mammals, in particular bats.
So, he found that the body temperature of a butterfly placed in a refrigerating chamber first slowly decreased to -10 ° C, then quickly rose to -1.5 ° C, and then dropped again to -10 ° C. This mysterious phenomenon of P. I. Bakhmetyev called the temperature jump.
It has long been known that substances can be in one of three states of aggregation: solid, liquid and gaseous. In this case, the solid state is subdivided into crystalline and amorphous. And when some substances pass from liquid to solid, their molecules also form crystals.
So, in 1938, the American scientist B. Layeth found that freezing organisms die as a result of ice crystals appearing in their bodies, leading to the destruction of cell membranes and cytoplasm.
Of course, suspended animation is a corresponding reaction of the body to certain environmental conditions: in particular, to a decrease or increase in temperature. The fact is that some animals, under circumstances so dangerous for their lives, store food, others migrate to more favorable and feeding places. And the third - they do not make reserves, remain in place, but they can plunge into a special state in which the activity of metabolic processes in the body is significantly reduced, which leads to a drop in temperature, heart rate, respiratory rate, etc.
Many species of molluscs, crustaceans, spiders and insects, as well as fish, amphibians, reptiles, birds and mammals, are immersed in hibernation.
Before going into hibernation, complex physiological changes occur in the animal's body. So, on the eve of suspended animation in body cavities, under the skin, along the intestines, fat accumulates in the chest. Moreover, these reserves are quite significant. For example, before hibernation, the weight of ground squirrels increases three times compared to the spring-summer season. And in one of the studies it was shown that in June, the weight of subcutaneous and internal fat in a marmot was only 10-15 g, and in August - 750-800. Dormouse, hedgehogs, brown bears, bats make significant fat accumulations.
Curious phenomena during hibernation occur in the body of the baribal black bear. So, during a 3-5-month sleep, he spends about 4000 calories every day, while not consuming food or water, and without removing metabolic products from the body.
This phenomenon was investigated by American scientists. It turned out that these features of the body of bears are due to the presence of a special hormone, which in the fall enters the tissues of his body from the hypothalamus.
However, this study did not answer a very important question: what prevents the accumulation of poisonous metabolic products in the body of baribal, which are excreted in the urine of an awake bear? In addition, it has been found that when a bear's body temperature drops significantly, it begins to tremble. And this continues from two days to a week - until the temperature returns to normal.
However, what surprised researchers the most was the bearish heart. The fact is that when during hibernation the bear takes a deep breath in and out, his heart does not beat at all for 10-20 seconds. What is the reason, scientists also cannot answer yet …
Scientists have known for a long time that all animals - from bears to gophers - hibernate regularly toss and turn in their burrows, awakening from deep sleep. But during these movements, a huge amount of energy so necessary for the animal is burned.
In connection with this phenomenon, researchers have developed a special interest in ground squirrels, in particular in Californian ones, which lie around for weeks with a body temperature of 5 ° C, and for six months their heart beats at intervals of only two beats per minute.
However, once a week, as if on command, they wake up. And of course, at this time, their body temperature rises. And up to as much as 37 ° C! If we calculate it, it turns out that the animal spends about 80% of the stored energy on these awakenings. This is definitely a terrible waste. What is it for?
To answer this question, American biologists observed these animals, taking 31 gophers as experimental specimens, each of which was attached with miniature temperature sensors. When the exhausted animals went into hibernation, they were injected with one of the carbohydrates, which increases the body temperature of awake animals. But this had no effect on the sleeping gophers. However, when they started to wake up, their body temperature immediately increased, as if they had been injected the day before.
In connection with these results, the only conclusion suggested itself: when the animal sleeps, its immune system is completely turned off and does not respond to stimuli.
But this situation is fraught with serious consequences for the gopher: pathogenic parasites can appear in his body during sleep. Therefore, to avoid this, the gopher wakes up and "turns on" its immunity. However, maybe animals have other reasons for these regular "wakes"?