Scientific research: do jellyfish live forever? The immortal jellyfish never dies a natural death.
As you know, any creature is mortal, and each representative of fauna or flora has a period of stay in the world of the living allotted by the Creator. This truth, considered an axiom, is being tried to refute by one of the unique species of coelenterates - the immortal jellyfish nutricula
(Turritopsis nutricula).
The discovery of the ability of this species of living beings to live forever excited the scientific community, the press and the media - after all, understanding the secret of immortality of tiny jellyfish nutricular gives hope to us, intelligent ones, if not to achieve eternal existence, then at least to extend our lifespan.
But let's take things in order.
Jellyfish Turritopsis nutricula has been known to the scientific world for quite a long time - its description was published back in 1857. The reproduction and life cycle of the nutricular is quite normal - fertilization of the egg by male reproductive products in sea water, the transformation of the egg into a planula, the settling of the planula on the substrate and the formation of a polyp, which buds into tiny jellyfish, and so on according to a well-known scenario.
Appearance of a jellyfish Turritopsis nutricula is also quite ordinary - a deep umbrella with a diameter of less than 5 mm is surrounded by a corolla of thread-like tentacles, of which newborn jellyfish have only 8, and in adult individuals can reach 80-100 pieces. Some “decoration” is a cross-shaped red spot formed in the center of the umbrella by the digestive organs of the jellyfish. Newborn nutriculars have no more than 1 mm in umbrella diameter - tiny and unattractive creatures.
But at the end of the last century, this animal revealed one of its amazing properties - the ability to live forever.
The laurels of the discovery of the immortality of this jellyfish belong to the Italian Fernando Boero, who quite accidentally discovered it in a dried-up aquarium, where, in addition to fish and other animals, several individuals lived Turritopsis nutricula, strange polypoid formations. Having examined the find more closely, the scientist noticed that these tiny polyps resemble jellyfish Turritopsis nutricula, but only without tentacles.
Surprised, Boero removed all the dead animals from the aquarium, leaving only a strange find, and filled it with water, deciding to check whether the discovered polyps were alive. After some time, they came to life and began to develop, then tiny jellyfish began to bud from the polyps. Turritopsis nutricula. 
The incredible happened - the nutricular cells reversed their development cycle - after all, in all known species of these coelenterates the medusoid form is final stage life cycle - after the sexual reproduction phase, jellyfish, as a rule, die, giving life to offspring in the form of fertilized cells that turn into planulae and then into polyps.
Jellyfish Turritopsis nutricula crossed out this scenario of the general development of hydroid coelenterates - under the influence of unfavorable factors that threatened them with death, they returned from adult animals to " childhood"The jellyfish threw off unnecessary tentacles, settled to the bottom, and turned into small polyps, which were easier to endure the hardships of dehydration in the aquarium.
Essentially, this fact can be represented as the return of an animal from old age to the childhood stage, and if this cycle is repeated endlessly, then theoretically it turns out that jellyfish Turritopsis nutricula capable of endless life.
Of course, not all organisms on Earth die of old age - enemies, diseases and extremely unfavorable living conditions often kill animals and plants long before their vitality reserves are exhausted. But sooner or later, everyone dies, but the immortal jellyfish is able to regain her youth and start life over.
Of course, one can argue - is this the same individual and the same jellyfish that turned into a polyp and gave birth to offspring? After all, the immortality of an individual animal or plant contradicts many postulates and laws of the development of life, including Darwin’s theory of evolution - each of the next generations of living beings acquires new qualities and properties that help it survive in conditions of fierce competition for a place in the sun. An organism capable of living forever does not develop and remains in its original form throughout the entire history of its existence, therefore it is a weak link in evolution - it has a high probability of dying from enemies and diseases that are constantly progressing and improving. 
Perhaps this is what is happening - no one has yet been able to discover a jellyfish whose age would be calculated in thousands of years - the discovery of the Italian Fernando Boero only theoretically “awarded” these animals with the ability of eternal existence. However, the ability Turritopsis nutricula to repeat the life cycle is unique and does not appear in other known creatures.
Jellyfish ability Turritopsis nutricula live forever even caused some panic and hypotheses in scientific circles - supposedly nutricular substances are capable of filling the World Ocean, displacing others known species aquatic animals, and thereby disrupt the biological balance of the planet. As evidence, the fact is mentioned that previously nutriculars were considered inhabitants of the waters of the Caribbean, and now they are found in many seas of warm latitudes.
But such hypotheses do not have a sufficient scientific basis - after all, nutricular tissues inhabit sea waters for more than one million years, nevertheless, they failed to upset the balance of life. In addition, jellyfish in general are a very resilient form of life, and the expansion of the range of individual species caused by climate change or other factors has long been known. In particular, the outbreak in different regions Nomura's jellyfish have recently been the subject of discussion among many scientific sources and media.
The taxonomy of the immortal jellyfish looks like this:
- Class: Hydrozoa
- Squad: Anthomedusae
- Family: Oceanidae
- Genus: Turritopsis
- View: Turritopsis nutricula(McCrady, 1857)
Recently, scientists have become interested in the jellyfish Turritopsis nutricula. How could such a simple creature attract such close attention of specialists, and even more so of geneticists? It's all about the next discovery. A certain scientist from Italy Fernando Boero (purely for his personal research) planted jellyfish of this species in an aquarium. Previously, no one had studied them thoroughly, probably because of their too modest size (5 mm) and absolutely nondescript appearance. For some reason, the scientist had to postpone his experiments, and he happily forgot about his pets. I remembered when the aquarium was already dry, and the inhabitants seemed to have already died. Boero decided to clear the aquarium of them and fill it with the next experimental subjects, but with his characteristic curiosity, he decided to study the already dried jellyfish.
Imagine his amazement when it was discovered that they did not die, but became larvae. He filled the aquarium with water again. After some time, the half-dried larvae became polyps, from which new jellyfish later budded. And so it turned out that the inconspicuous Turritopsis nutricula is an immortal jellyfish that accomplishes the seemingly impossible. She independently controls her genes and can “move backwards,” that is, she returns to the original stage of development and begins to live anew. In other words, the immortal jellyfish Turritopsis nutricula cannot die due to old age. She only dies if someone eats her or tears her into pieces.
Today, scientists believe that the tiny immortal jellyfish is the only earthly organism that can independently rejuvenate and regenerate. Moreover, she will repeat this cycle countless times. The immortal jellyfish Turritopsis belongs to the genus Hydroids, whose representatives live in the seas of temperate and tropical zones. This genus includes marine colonial coelenterates, namely polyps, the colonies of which consist of several hundred individuals. They are like bushes, motionless and securely attached to the substrate. Although there are also loners. In a colony, the intestinal cavity of an individual polyp is connected to a common intestinal cavity that runs through the entire colony. In other words, they are all united by a “common gut” through which all ingested food is distributed.
The immortal jellyfish has a dome-shaped umbrella, along its edge there is a corolla of tentacles. Moreover, the number of tentacles increases with age: a newly budded jellyfish will have no more than 8, and later the number will increase to 90 pieces. The jellyfish has two stages of development: the first is the polyp, the second is the jellyfish itself. As the latter, it can exist from several hours to several months, and then returns to the first stage, endlessly repeating this cycle.
The immortal jellyfish comes from the Caribbean, but today it is already found in other geographical areas. This happened because Turritopsis nutricula multiplied greatly. Some believe that such an increase in numbers may lead to an imbalance in the world's oceans. But Maria Miglietta (Doctor of the Institute of Tropical Research) is sure that there is no need to worry about filling all the reservoirs of this species with hydroids. Turritopsis nutricula has too a large number of predator enemies who are engaged in the extermination of their offspring. Although, this is probably not enough, since the number of immortal jellyfish is only increasing every year.
Scientists have been studying hydras and jellyfish for their ability to regenerate for a long time. Since the 19th century, theories have been put forward about the possible theoretical immortality of such organisms. As it turned out, they were not groundless. At the end of the 20th century, the jellyfish Turritopsis nutricula was recognized as the only known creature that can live forever. Is it really? How did the immortal jellyfish Turritopsis nutricula solve the problem of eternal youth for itself?
Characteristic
Jellyfish of this hydroid genus live in the seas temperate zone and tropics and belong to the family Oceaniidae from the order Anthoathecata. The jellyfish Turritopsis nutricula (photo can be seen in this article) is a eukaryotic animal with stinging cells. These coelenterate organisms have two stages of development.
At first life path They develop in the form of polyps, and reach sexual maturity as jellyfish. Most representatives of this class live relatively short life, which rarely lasts more than 3-4 months. After reproduction, they usually die. However, the immortal jellyfish Turritopsis nutricula does not fit into this scheme.
Structure
The homeland of the species is the Caribbean. The size of the jellyfish is small, it is 5 mm in diameter. The body shape is dome-shaped, resembling an umbrella, along the edge of which there are tentacles with stinging cells. She grabs food with them. IN different period development, the number of tentacles changes. With age, there are more of them: from 8 in young individuals and up to 90 in sexually mature ones.
The jellyfish Turritopsis nutricula swims with its mouth down. It serves both for receiving food and for removing its remains. The body is 95% water. Nervous system arranged primitively. A jellyfish has no brain, skeleton, or heart. However, it reacts to irritation: food, mechanical stress, changes in the composition and properties of water.
After reproduction, the jellyfish does not die. It is noted that it sinks to the bottom, attaches with tentacles to a suitable surface and gradually turns into a polyp, from which a young individual will subsequently grow.
Immortal jellyfish Turritopsis nutricula: life cycle
Representatives of this species, like many other hydroid organisms, experience two stages of development. The larvae that develop in the mother's body after fertilization of the eggs, when they fall into the water, sink to the bottom, become attached there and turn into polyps. Their colonies are spindle- or club-shaped.
The body of such a formation has a cuticle on the surface, which acts as a skeleton. Even then they have thread-like tentacles with stinging cells. The captured food is ingested and distributed among the entire colony. Young jellyfish bud off from this formation, cease to be a sedentary form and set off to swim.
Features of such a creature as the immortal jellyfish Turritopsis nutricula
Why did the immortal genus Turritopsis become so widely known and characterized? This is due to the tendency of hydroid organisms to undergo regeneration processes. It was known before that the lost part of the body of a jellyfish short term grows back. If you cut it, a new individual will soon develop from a separate fragment.
This process is called transdifferentiation. During this process, the cell transforms from one type to another. Such features are also present in some other organisms that are more complex in structure. So, for example, a lizard can regrow the tip of its severed tail. Animal and human stem cells can be used to grow certain organs.
However, the jellyfish Turritopsis nutricula, it turns out, can do this with its entire body. It is worth making allowances for the fact that, after all, its body is quite simple, the cells have relatively low differentiation, so it is easier for them to transform, and, in addition, there are two phases of development. Actually, the jellyfish does not live permanently - its stages change.
History of discovery
This breakthrough in science was not planned. Fernando Boero, an Italian natural scientist, at the end of the 20th century, during the process of research, allowed the water in his aquarium to dry out, where there were jellyfish of the genus Turritopsis nutricula. Deciding to continue the experiments, he again filled it with water. To his amazement, Boero discovered that the jellyfish did not die, but miraculously turned into polyps. Over time, young individuals grew from them and budded off.
Further laboratory research confirmed this fact. At unfavorable conditions environment, the process of reverse development began in jellyfish. Sudden changes in temperature, changes in water salinity, mechanical damage, lack of food - all this acted as a catalyst and provoked the jellyfish to spring into action. defense mechanism. They sank to the bottom and were reborn into a young individual through the polyp phase.
Thus, scientists have made the assumption that the immortal jellyfish Turritopsis nutricula is the only immortal creature known to science at this stage. The duration of observations is still relatively short, but experiments have been able to establish and testify to the ability of this species to rejuvenate dozens of times in a row.
Warning
How and to whom does the immortal jellyfish Turritopsis nutricula threaten? Why is an immortal species a threat to the ecosystem? Since their discovery, there has been serious interest in these organisms. It has been noted that from the Caribbean, jellyfish have spread throughout the world's oceans. The theoretical immortality of these organisms gives rise to speculation about their excessive reproduction. In this case, there is a possibility of imbalance in the ecosystem.
Is there really a danger? Theoretically, it exists. However, it is believed that these jellyfish appeared many millions of years ago. If during this time they have not changed the balance, then is there any point in sounding the alarm? The creatures are relatively small, at a young age Many ocean inhabitants feed on them, so there is no threat of overpopulation yet.
The ability to increase in numbers, confirmed by experiments, cannot be assessed as a threat to the ecosystem. The absolute infinity of the life cycle of these organisms has not yet been proven. Observational practice is short, and a longer period of time is needed to confirm this theory.
Turritopsis is thought to have originated in the Caribbean but has spread widely throughout to the globe. Most often, jellyfish can be seen in the Mediterranean Sea and off the coast of Japan. This species of jellyfish is virtually immortal, and some scientists, such as the Smithsonian Tropical Marine Institute, speak of a "worldwide silent invasion."
Biological immortality
Of course, you can kill a jellyfish. And it’s easy to do this without even noticing it. Physical immortality has not yet been found in any living organism on our planet. Most of all jellyfish species live from a few hours to many months before they die, and Turritopsis dohrnii is able to return to the state of a polyp - to the very first stage of the life cycle of cnidarians. Experiments in the laboratory have shown that a jellyfish can begin to “develop” in the opposite direction at any stage of life. Her dome and tentacles stop growing, then various processes and shoots appear on her body, which are overgrown with feeding polyps. As a result, the jellyfish returns to the stage hydroid.
This ability to change the life cycle is observed as a reaction to unfavorable living conditions. If something goes wrong in the life of Turritopsis dohrnii, it can always “return” to its childhood to try everything again. Currently, this is the only living organism of its kind. In the laboratory, 100% of all observed jellyfish were able to return to the polyp state, although in natural conditions Scientists were not lucky enough to observe such a degeneration. This is partly due to the transience of the process, and being in the right place and in right time, and even with photo or video equipment it didn’t work out.
It must be said that the content of immortal jellyfish in artificial conditions- the matter is very complicated. Currently there is only one scientist Shin Kubota(Shin Kubota) from Kyoto University (Kyoto, Japan), contains a group of jellyfish for quite a long time - more than 2 years. According to the scientist, during this time his colony completely regenerated itself 10 times. The experiment continues today. The jellyfish colony is monitored daily to ensure that the animals are properly digesting the brine shrimp they are fed. Shin Kubota often appears in Japanese science media and even wrote several songs about his jellyfish.
Despite this remarkable feature, most jellyfish are devoured by other animals that feed on plankton. Therefore, it is too early to talk about a “worldwide invasion of immortal jellyfish” into the world’s oceans.
Everyone wants to live long, preferably forever. Pharaohs, tyrants of the past and present, rulers of the “free world” would give a lot for the elixir of immortality that prolongs mortal existence. It is unlikely that such medicine would be available ordinary people. So far such a miracle drug has not been found, but the search does not stop. Priests, alchemists, genetic scientists, microbiologists, pharmacists, any possibility of creating such a medicine, even if it does not make a person’s life eternal, but long, without symptoms of falling into childhood. Therefore, the immortal jellyfish Turritopsis nutricula aroused the suspicion of the scientific world with its incomprehensible behavior back in the 19th century. And at the end of the last century it became clear to them that this is probably the only living organism on planet Earth that ignores the usual life cycle.
Phoenix living in the ocean
Having created a sensation in the academic and pseudo-scientific environment, the immortal jellyfish Turritopsis nutricula, with a diameter not exceeding 5 mm and generally similar to all other fellows, lives quietly in the tropics and temperate climatic zone– from Caribbean Sea to Japan.
The fact that the hydroid jellyfish is immortal can be concluded from the following facts:
True, scientists conducted experiments on land, and not in their usual habitat - the ocean, and were also unable to prove the presence of individuals in it, whose age is estimated at thousands of years. But even such amazing results gave both food for thought and hope for a scientific solution to the mechanism of immortality.
Immortal life
Since the hydroid jellyfish is immortal, then why are we worse? - not only idle journalists and inquisitive bloggers who joined them, but also some scientists who foresaw the future glory of humanity’s benefactors and multiple Nobel Prize, turning into applause.
Alas, not everything is so simple on the thorny path of knowledge. And now the joyful exclamations gave way to boring explanations, replete with terms in Latin, why it has not yet been possible to produce the treasured medicine.
Seriously, the point is most likely that a person and a jellyfish, although both living creatures, consist almost entirely of water, but that’s where most of the similarities end. What is good for jellyfish is not necessarily useful for people.
However, the immortal jellyfish Turritopsis nutricula gave hope to humanity. After all, she is alive clear example of cheating death. The jellyfish found him, now it’s the people’s turn.
