27 December 2021

These immortals

What creatures on Earth live forever

Svetlana Koroleva, Russian Seven

Everything on Earth has its beginning and, of course, the end of existence. However, scientists can name several biological species that can live almost forever if they are not destroyed by an external factor. So what are these animals? Surprisingly, there may be organisms on our planet whose age scientists date... 10 thousand years. That is, even now that Scolimaster (or scientifically Anoxycalyx joubini), which was born simultaneously with the first Egyptian pyramids, lives quietly somewhere in the Arctic waters. Such an animal belongs to a species of six-ray sponges from the Rossellidae family of the order Lyssacinosida. Adults can reach a length of up to 2 m and a diameter of up to 1.7 m . The color of sponges varies from pale yellow to white, and icy waters and ocean depths from 45 to 441 m are suitable for their extremely slow metabolism.

For the first time such sponges were discovered during the French Antarctic expedition of 1908-1910 under the leadership of polar explorer, oceanographer and physician Jean-Baptiste Charcot. In 1916, this representative of the fauna was also described by a French specialist, curator of the Zoological Museum in Strasbourg, Emile Topsen, and the species itself was named after the French zoologist, professor of the National Museum of Natural History in Paris, Louis Joubin.

That is, scientists around the world have been studying Scolimaster for more than 100 years, but so far they only know that this unique creature has the slowest metabolism and the lowest oxygen consumption on the planet.

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Another immortal inhabitant of the depths of the sea is the jellyfish Turritopsis Nutricula. This creature belongs to the genus of hydroids from the order Anthoathecata and prefers to live in a tropical or temperate climate, that is, its life does not depend on a slow metabolism caused by low temperatures. Then how does this jellyfish achieve immortality?

In the 1990s, European oceanologists discovered that jellyfish of this genus, perfectly reproducing, forming a polyp inside themselves, are themselves able to turn back into an embryo. At this moment, the old "body" of the hydra, having sunk to the bottom, dies, a small polyp remains from it, from which a new jellyfish grows over time. She can also produce offspring and sink to the bottom again to become "small" again. Such a cycle of life in Turritopsis Nutricula occurs endlessly.

However, in 1996, Italian scientists from the Thalassographic Experimental Institute in Rome did not immediately succeed in achieving this process in laboratory conditions. Jellyfish certainly died, until the researchers guessed not only to arrange for them sudden changes in water temperature and salinity, but also to cause mechanical damage to the bodies of hydra. Only then did the somatic cells of these jellyfish, which had undergone differentiation, become involved in the occurrence of metamorphosis. That is, for the appearance of the "immortality" function, the jellyfish needs a "threat to life".

Until now, scientists are studying their stem cells, since the transformation potential of Turritopsis Nutricula has no analogues in the animal kingdom.

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Many animals are able to hibernate in the cold season. However, the tardigrade thus experiences all possible adverse conditions, and then wakes up and lives on. The cycle of its existence can be endless. But how does this happen?

This type of microscopic invertebrates, close to arthropods, was described back in 1773 by the German pastor I.A. Goetz as a "small water bear". The body of slow walkers is no more than 1.5 mm, translucent, consists of four parts and a head. The creature has four pairs of short and thick legs with one claw at the end. Slow walkers really move very slowly, only at a speed of 2-3 mm per minute. They feed on microparticles of algae and mosses, but if there is no food, or the temperature is too high or low, the tardigrades lose their body moisture and in such a "dried" state, falling into suspended animation, wait for better times.

Lazzaro Spallanzani, an Italian naturalist and physicist of the XVIII century, who was the first to describe slow walkers and their process of "resurrection from the dead", noticed that the surface of the bodies of these animals is covered with a hard "wax" shell, thanks to which the "mummy" can withstand enormous loads without harm to further life.

A group of researchers from the University of Tokyo, who described the sequenced genome of slow walkers in 2015, also told how these animals in a cryptobiotic state withstand a long stay in the cold airless space of space, experience high radiation radiation, electric shocks, and then return to normal, crawl again and reproduce. Such a thing will never be subject to the human body.

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Jellyfish, arthropods, insects, all of them are far from humans by their genetic nature and the possibility of their immortality gives scientists little to find an effective medicine that can increase life expectancy. However, the naked digger, also considered an "immortal" animal, is a mammal, although it is cold-blooded. This small burrowing rodent, with a body length of 8-10 cm, a tail of 3-4 cm and a weight of 30-35 grams, belonging to a species in the genus Heterocephalus and the family Heterocephalidae, traditionally lives in eastern Africa, organizing underground social colonies. Animals have a slow metabolism, the ability to live with very low oxygen levels and high concentrations of carbon dioxide. They have no fur, and at the same time their skin cells are devoid of neurotransmitters responsible for transmitting pain impulses to the central nervous system. Therefore, naked diggers do not feel cuts, burns, acid exposure and they are practically immune to cancer. Richard D. Alexander, an American zoologist and professor at the University of Michigan, considered diggers to be neotenic animals. That is, by nature, their body is able to stop the program of individual development at the newborn stage in order to possess the qualities necessary for survival. That is why gerontologists all over the world have been investigating the neotenic properties of the naked digger for many years. For example, a group of biologists led by Academician Vladimir Skulachev, director of the A.N. Belozersky Research Institute of Physico-Chemical Biology at Lomonosov Moscow State University is studying the secrets of longevity of these animals in order to try to pass them on to humanity. Today, scientists already understand that the possibility of "disabling" the aging of the body in naked diggers arose as a natural compensation for the fact that 80% of these individuals do not participate in reproduction because of their social roles in the colonies where they live. In humans, a similar "gift" of nature can provoke the extinction of all mankind.

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