How can you tell the age of a shark. The scientist calculated the true life span of sharks. Shark attacks on people, or killer sharks
To date, not everything is known about sharks. Nevertheless, they arouse the constant interest of people. More than one encyclopedia has been written about them. Not all species are dangerous to humans. They themselves suffer greatly because of the people. Every year, up to 100 million individuals die due to fishing.
Who are sharks? They first appeared 450 million years ago. Since that time, these creatures have not changed much. The shark is a fish that lived in the oceans long before the dinosaurs.
In total, there are about 450 species of sharks on the planet. Among themselves, these cartilaginous fish differ greatly. The largest of them reaches a length of 20 m, while the length of the smallest is only 17 cm. Some of these predators, inhabitants of the depths, with the help of special organs are able to glow, luring prey.
How many years do sharks live? The answer to this question will be individual for each specific species. Polar are real centenarians. The life expectancy of this species of shark is over 100 years. For more than 70 years, the life of a whale lasts. How long do these predators live on average? In most species, life expectancy varies from 20 to 30 years.
The life of sharks is subject to a complex hierarchy that operates not only within one species, but also between representatives of different varieties. A significant number of species of these fish coexist with each other in large groups.
They swim at low speed most of the time. The average shark speed ranges from 8 to 9 km/h. During a throw at a potential victim, they are able to noticeably accelerate. Mako shark is considered the fastest. It is capable of speeds up to 50 km/h.
Anatomical data
Different types of sharks differ from each other in external data. The size of these animals can vary greatly. What do sharks look like? The fish have a streamlined body shape, a tail fin of a special shape, as well as two dorsal, anal, paired ventral and pectoral, many teeth growing in several rows. The closest relatives of these creatures are rays.
The structure of the shark is different than that of other fish. These predators are cartilaginous fish. The name refers to one feature of the anatomy of sharks. Their skeleton does not consist of bones, but of cartilage.
The scales of the predator are arranged in such a way that the tips of the scales protrude outward from the skin. They are very close to each other, due to which the skin of a shark can appear both smooth if you run your hand in the direction from head to tail, and hard, rough, resembling sandpaper, if you stroke a marine predator in the opposite direction.
The teeth of these predators grow in several rows, their structure varies in different species and depends on what this fish eats. If for some reason the shark loses a tooth, the one in the previous row will take its place. In the very last row, after a while, a new one will grow. How long this predator lives, her teeth grow so much. The device of the dental apparatus can tell a lot about sharks.
Physiology
How do sharks breathe? The shark is a fish, and it breathes in the same way as other chordates. For this, a special organ is used - the gills. The gill sacs of the shark open inward into the pharynx and outward on the sides of the head. Gill slits can be from 5 to 7 pairs. Cartilaginous fish use gills only for breathing.
Most of these marine predators are cold-blooded animals. Only a few species are partly warm-blooded. In these species of sharks, thermoregulation is different from others. They are able to maintain body temperature 9-13°C warmer than the surrounding water. However, such a temperature difference does not apply to the entire body of the predator. Near the gills and heart, the temperature will be equal to the ambient temperature.
Because sharks don't have a swim bladder, they have to be constantly on the move. The need to constantly swim is due to the fact that most of these fish are not able to pump water through the gills on their own. This is used by shark hunters. If you pull the shark down by the tail for a while, water will not flow into its gills. In this case, the predator may drown. However, there are exceptions to this rule. One of them is the nurse shark, which is able to maintain the respiratory system while lying on the bottom.
How does a shark compensate for negative buoyancy? Compensation occurs due to a decrease in body weight. This helps the cartilage skeleton, which is much lighter than the bone, as well as the accumulation of carbon in the liver. To make it easier to swim, the skin is covered with a thin fatty film. Some predators create positive buoyancy in a different way. They swallow air, creating a makeshift swim bladder from their stomach.
Food and hunting
What do sharks eat? The answer to this question will be different for different types of marine predators. Sharks are all carnivores, but their food preferences vary. Since these marine animals spend a lot of energy on constant movement, they need to consume a large amount of fatty foods.
Most species do not attack humans. Only rare predators are dangerous.
The tiger shark, which feeds on everything that comes its way, including inedible objects, has earned the title of marine scavenger.
The largest shark, the whale shark, eats plankton. In the process of feeding, she swims very slowly, developing a speed of no more than 1 m / s. The teeth of this species of shark are not designed to grip flesh. They are needed to keep plankton in the mouth. For humans, this type of shark is safe. In addition to the whale shark, there are 2 more types of sharks that feed on plankton.
The main diet of the great white shark consists of fish, pinnipeds, dolphins and porpoises. In addition, this predator can also eat carrion. Man is not the habitual food of beings. They attack people by mistake.
The main food in the diet of many sharks is fish. Cases of cannibalism are not uncommon. For this reason, cubs often live away from adults.
How do these creatures get their food? The answer to this question depends on the type of food of a particular species. The largest creatures feed on zooplankton, which they catch in a wide-open mouth, swimming through aggregations of krill at low speeds. Some believe that these giants are sharks without teeth. They have teeth, but they are not designed to tear meat out of the victim's body.
Small creatures prey on schooling fish.
Larger species prey on larger prey. Often they lie in wait for prey, swimming around it in circles, after which, having waited for the right moment, they make a sharp jerk, attacking the victim. At the time of the throw, this fish develops a speed that is much higher than usual. Such throws take a lot of energy and strength. How fast are these throws? From 19 to 50 km/h, depending on the type.
They can hunt alone or in packs.
Habitat
Where do sharks live? The habitat depends on the species. In addition, some make migrations.
The habitat of most of these fish is sea water. There is only one species that is found in the fresh water of Lake Nicaragua.
Most of the small species prefer to settle off the coast in warm seas. Larger swim in the open sea. Most often they can be found close to the surface. There are few who prefer to live in the depths. There are only a few species that live in pitch darkness. Luminous sharks descend to a depth of more than 6 thousand meters during the day, and rise closer to the surface at night. Little is known about the sharks of the depths. The choice of the place where the shark lives depends on what kind of food it prefers, size, habits.
You can meet these fish in most seas. In addition, sometimes they swim into the mouths of the rivers, rising quite high upstream.
reproduction
How do sharks breed? Despite the fact that the shark is a fish, it does not spawn. According to the type of reproduction, they can be divided into 3 types: viviparous, ovoviviparous and oviparous. These fish are characterized by internal fertilization.
Livebearers develop multiple embryos. In some species, babies eat each other even in the womb. Because of this breeding feature, sharks sometimes have 2 queens.
Live birth differs from ovoviviparity in that in the first case, a placenta is produced in the mother's body, which ensures the exchange of substances between the mother's body and the embryos. In the case of ovoviviparity, such a metabolism does not occur. In this case, the cubs hatch from eggs in the body of the female, after which they are born. They get all their nutrients from the yolk.
Oviparous lay on average 1 to 12 eggs. The only one that puts off much more is the polar one. She lays up to 500 eggs at a time.
How long does pregnancy last? The answer to this question depends on the species. The whale bears offspring for more than 2 years. Pregnancy frilled nose lasts 3.5 years. The nurse shark carries embryos for 2 years, after which 1 cub is born from each of its uterus.
Maternal instinct in most of these fish is absent. A mother can eat babies that she recently gave birth to. In a tiger predator, nature dulls the hunger before childbirth, so that the young have time to flee. Some time after the female gives birth, the instinct is restored. Therefore, young animals live separately from adults and are found mainly in shallow water. Only a few species of these predatory fish take care of their own children.
If there are no males, then the shark will switch from sexual reproduction to asexual. This often happens in captivity. In the wild, cases when this fish breeds in this way have not been recorded.
Fishing victims
Every year in the world from 40 to 100 million of these creatures become victims of fishing. They are caught for their fins, which are considered a delicacy, the skin from which bags, briefcases, suitcases, shoes, teeth, liver and cartilage are made. Some time ago, cartilage extract was considered an effective remedy for cancer. Although the effectiveness of this drug has not been confirmed, shark cartilage is considered a source of vitamins. The same applies to the liver. Teeth are used as souvenirs.
The fins are considered the most valuable part. Often these fish are caught just for their sake. Having cut off the fins, the fishermen throw the carcass overboard. At this point, the shark is often still alive. A predator left without fins has no chance of survival. She cannot move and hunt on her own, because speed is required to catch food, and she will become an easy prey for another predator or die from suffocation.
In recent years, in many countries of the world it was forbidden to catch these fish only for the sake of fins. Before cutting off the fins, fishermen must provide the whole carcass.
Monsters of the past
The largest shark that has ever existed is the giant megalodon. The classification of the megalodon is controversial. This extinct underwater giant is currently the largest fish of all time.
Megalodon became extinct over 2.5 million years ago. Only numerous remains have survived to this day. This huge fish was the owner of a frightening dental apparatus. Reaching a length of up to one and a half dozen centimeters, jagged along the edges, his teeth grew in 5 rows. No other animal on the planet had larger teeth. The giant jaw of sharks of the distant past is larger than human height. Currently, they are very expensive and are sold at auctions.
What do sharks of the past look like? It is assumed that the megalodon was similar to the modern large white, but of a larger size. Not one of the fish existing in our time has similar sizes.
At the moment, not everything is known about the sharks of antiquity. Some researchers suggest that in reality the megalodon is not extinct, but this has not yet been proven.
The closest relative of the megalodon is the now extinct megalolamna. Little is known about sharks of this species.
Oksana Alexandrovna Pochepa is a famous Russian pop singer performing under the pseudonym Akula. The girl managed to become famous back in the distant 90s thanks to the hit song “Acid DJ”. At that time, she was one of the most popular singers in Russia and traveled on tour not only throughout her native country, but also in Europe and the States.Since that moment, she managed to shoot several dozen videos and even become the main character of the scandal that revolved around the actor Mel Gibson. The girl also showed herself as an actress, playing a small role in the film "Street Racers" (2009) and starring in the short film "109 years at least".
Childhood and family of Oksana Pochep
The future star of Russian pop music was born on July 20, 1984 in Rostov-on-Don. Her older brother Mikhail was already growing up in the family. Since childhood, Oksana has shown creative inclinations in various fields of art. 
And yet, the girl's vocal abilities were especially pronounced. Noticing her daughter's talent for singing, her parents, without hesitation, enrolled her in several creative circles. Thus, already from childhood, the girl sang as part of the city ensemble and performed solo with songs of her own composition.
In parallel with this, she was engaged in acrobatics. Oksana admitted that if she had not become interested in singing so much, she would definitely have continued her sports career.
The beginning of the singing career of Oksana Pochep
In 1991, Pochepa began studying at the music school. Rimsky-Korsakov. To be more precise, it was her father who advised her to go there. In the past, Alexander Pochepa also wanted to be creative, but life turned out differently, so he did his best to help his daughter make her wishes come true. She, a little genius, was accepted at the beginning of the 3rd quarter.Duet of Oksana Pochep and her father Alexander Pochep
Oksana started her professional singing career quite by accident. To support her friend, she went with her to the audition, which was conducted by the VJ of the local radio station Andrei Baskakov, who was recruiting soloists for the new musical project "Youngster". Unfortunately, her friend was left with nothing, but Oksana managed to get around a hundred competitors and charm Andrei. Thus, already at the age of 14, she signed her first contract and began to earn money by singing.
Being a "Youngster", Oksana performed on the largest stages of her native city, even in the Rostov Palace of Sports. In addition, she had the opportunity to go on the Youth Against Drugs tour, and then on tour to Germany. Repeatedly, the girl performed with other stars of that time, among which was the famous rapper Decl and Legalize. She soon attracted the attention of the famous performer and producer Sergei Zhukov.
Oksana Pochepa aka Shark
Zhukov invited the girl to become the central figure of his new musical project Shark. After analyzing this proposal and consulting with her parents, Pochepa, of course, agreed and soon went to the capital. With considerable experience behind her back, Oksana already knew what to expect from the music business. The girl worked on herself daily, recorded new songs and practiced vocals.Just a year later, the 17-year-old Shark released her debut album, Acid DJ. The song of the same name and the album as a whole made such a splash in the musical field that the girl instantly became a new star. The title track of the album was played on all music TV channels and rotated wildly on the radio. Soon the tracks "Little" and "Running" were released, and in 2003 the album "Without Love" was released.
Oksana Pochepa (Shark) - "Acid DJ"
At this time, difficulties began in the life of the singer. Because of such an early start in her musical career, it becomes more and more difficult for her to overcome fatigue and stress every day. During the world tour, Oksana flew to America with performances, where she remained until 2006.
However, she did not leave music overseas either. Pochepa continued to perform, but she managed her time on her own. The love of loyal fans made her fly to her homeland, who regularly sent letters to the idol with words of support and requests to return back. In 2006, Akula released her third album called "Such Love", which included 13 songs and 2 remixes.
Oksana Pochepa - "Girlfriend"
In 2007, the girl shot a video for the song "Morning Without You". Soon, Oksana and Sergey Zhukov terminated the contract, so the singer went on a solo voyage. For some time she was the host of the most popular hit parade "Uni-hit" on the radio station "Youth", after which she returned to her singing career under her own name, giving the public a lot of incendiary dance hits and lyrical compositions.
Personal life of Oksana Pochep
The relationship of the popular singer has always been as unpredictable as the girl herself. Unfortunately, we know few details about her personal life, but in 2009 Oksana was involved in a scandal involving the name of the famous actor Mel Gibson. At that time, a happily married Hollywood hero was spotted on the beach in the company of his mistress. Over time, the name of the girl became clear - Oksana. Very soon, the media found out her full name and occupation. 
The singer was not taken aback and confirmed that it was she who destroyed the marriage of a popular actor. But the more questions journalists asked, the less certain her story became. In the end, it became clear that the real mistress of the actor was another girl named Oksana, and Pochepa just used the name Gibson for her own PR.
Oksana Pochepa today
2013 was marked by a significant date for the singer - 15 years of her singing career. In this regard, Oksana arranged a big concert, which was attended by a record number of listeners.Oksana Pochepa (Shark) - Melodrama
In 2014, she released a new solo album, Zvezda, which included 14 tracks. In the autumn of the same year, the singer performed at the opening of the stadium of FC Spartak. In 2015, Oksana Pochepa pleased the audience with two new songs: "Farewell, Berlin" and "Melodrama".
Study of the lenses of the eyes of the Greenland shark ( somniosus microcephalus) showed that the age of its large individuals is about 400 years. Moreover, such a life expectancy is the rule for this species, and not the exception. Apparently, the Greenland shark is the longest-lived modern vertebrate animal.
Death, oddly enough, is a relatively new invention of evolution. The first inhabitants of planet Earth, bacteria and archaea, were potentially immortal. Single-celled creatures can, of course, die from a variety of external causes, but they do not have a programmed death that necessarily ends each life cycle and leads to the formation of a corpse. It appears along with the multicellularity associated with sexual reproduction. Back in 1914, a fairly well-known zoologist, Professor Evgeny Alexandrovich Shults, wrote about this:
« Nature had all the means to make the individual immortal, but she chose death for him. Instead of constantly rejuvenating individual organs - through the rejuvenation of their cells - she chose the rejuvenation of the whole organism with the help of a single cell. She took immortality from us and gave us love in return.».
It looks like Schultz was right. It does not follow from any known laws of nature that any multicellular organism must necessarily grow old and die. Now, for example, we know that individual individuals of coral polyps can live for more than four thousand years, and there is no reason to believe that this age is the limit (E. B. Roark et al., 2009. Extreme longevity in proteinaceous deep-sea corals). True, this has been established for such polyps in which the individual is part of the colony. Independent organisms, and especially those with complex nervous systems, as a rule, have a limited lifespan - each species has its own.
For example, lifespan in mammals has been shown to be inversely related to metabolic rate and directly related to relative brain size (M. A. Hofman, 1983. Energy metabolism, brain size and longevity in mammals). In other animals, such dependencies are certainly more heterogeneous and more complex. However, among mammals there are special cases. The most famous of them is the naked mole rat ( Heterocephalus glaber), an African rodent that is eusocial, similar to social insects. A colony of diggers resembles a termite mound in many ways - it consists of a "womb" (reproducing female), her two or three "husbands" and several dozen "workers" of both sexes who do not breed. At the same time, naked mole rats practically do not age and can live for more than 30 years; for mammals of this size, this is a unique case (see Naked mole rat genome - the key to the secret of longevity? "Elements", 11/11/2011). The absence of aging, which leads to a huge increase in life expectancy - ten times compared to mice and rats - allows working individuals that do not spend resources on their own reproduction to take care of many generations of newborn descendants of the uterus in a row. But the most interesting thing in this story is the ability to “turn off” aging if there is an evolutionary “request” for this. Naked diggers show us that this possibility exists. And this opens up a huge field for research.
To what values, in principle, can the individual life span of a complex multicellular animal - for example, a vertebrate - reach, and is there any natural limit here at all? To find out, we must first understand how long vertebrates actually live in nature. And it's not always easy. But little by little the facts are accumulating. An interesting new piece of information on this topic was recently presented to scientists by the Greenland polar shark (Fig. 1).
Meanwhile, Greenland sharks can also be six meters long (according to reference books, their maximum recorded length is 640 cm). Even more amusing, it has long been known that female Greenland sharks reach sexual maturity at a length of about four meters. And now, based on the collected data, it can be argued that they reach this length at the age of about 150 years. Only then does the Greenland shark become an adult.
So, it turns out that the Greenland shark is the longest-lived vertebrate in the world. Previously, the bowhead whale was considered to be such, which can live up to at least 211 years (see. A new database on the life span of vertebrates AnAge has appeared on the Internet - the most complete and accurate, "Elements", 06/15/2009). Interestingly, this estimate was also obtained using the analysis of the chemical composition of the lens of the eye (J. C. George et al., 1999. Age and growth estimates of bowhead whales ( Balaena mysticetus) via aspartic acid racemization). But the Greenland shark, so to speak, lives even more slowly. In general, there is nothing striking here, the new data fit well into the well-known trends: with a large size and a deliberately low metabolic rate (a cold-blooded animal cannot have another in the icy ocean), slow development is quite natural. But the specific age figures obtained are, of course, impressive. I wonder if some vertebrates can have even more of them?
Not a single news publication in the world skimped on high-profile headlines on this topic:
There are creatures in the sea who could see Shakespeare.
Shark hardening: Scientists have found that Greenland sharks live for 400-500 years.
Scientists have discovered the longest-lived vertebrate animal.
The oldest 400-year-old shark lives in the cold waters of Greenland.
Fishermen caught a long-lived shark born during the time of Ivan the Terrible.
Scientists have named the possible age of the oldest animal on the planet.
This shark, caught by scientists, lived under Columbus.
The life span of the Greenland polar sharks can exceed 500 years.
Biologists managed to find the oldest animal in the world.
Its growth rate is reported to be less than one centimeter per year. Previously it was already known that these sharks are long-lived creatures, but how long they live was a mystery.
Marine biologists and the lifespan of bowhead sharks for decades without success, said Stephen Campana, a shark expert at the University. - Considering that this shark is a dangerous predator (king of the food chain) in the waters of the Arctic, it is incredible that we did not know whether this shark lived for 20 years or 1000 years.
The Greenland shark was first sighted near the surface of the water from the research vessel Sanna in North Greenland.
Julius Nielsen says this is the first hard evidence of how long these creatures can live:
We assumed that we were dealing with an unusual animal, but the fact that the sharks turned out to be so old came as a real surprise to us!This certainly tells us that this creature is unique and should be considered as the oldest animal in the world.
Video - the longest living vertebrate animal on the planet:
A publication in the renowned scientific journal "Science" (August 2016) by Nielsen and his international team of researchers (specialists from the UK, Denmark and the USA) describes how they determined the age of 28 female bowhead sharks during scientific research between 2010 and 2013 .
It turns out that the age of many fish can be determined by counting the growth of layers of calcium carbonate - "stones" in. This technique is somewhat similar to counting annual rings on a tree.
The complexity of the study was that sharks do not have such stones. But Greenland sharks have plenty of other calcium-rich tissues that are suitable for this type of analysis.
In addition, the research team relied on various approaches, for example, studying .
The lens of the eye consists of proteins that accumulate over time, as well as proteins in the very center of the eye, which are still formed and remain unchanged throughout the life of the fish.
Determining the date of occurrence of these proteins allowed experts to determine the age of the shark.
To determine when proteins were formed, scientists turned to radiocarbon dating, a technique that relies on determining the levels of a type of carbon known as carbon-14 in a material that undergoes radioactive decay over time.
By applying this technique to the proteins at the center of each lens, the scientists deduced a wide range of ages for each shark.
The scientists then used a "side effect" of a test that took place in the 1950s: when the bombs were detonated, they increased the level of carbon-14 in the atmosphere.
The momentum in carbon-14 entered the marine food web in the North Atlantic no later than the early 1960s.
This gave us useful timestamps,” Nielsen says. – I want to know where I will see the impulse in my shark, and what time does it mean: is it 50 or 10 years old?
Nielsen and his team found that the lens proteins in the two smallest of the 28 bowhead sharks contain large amounts of carbon-14, suggesting they were born after the early 1960s.
The third small shark, however, showed slightly higher levels of carbon-14 than 25 large sharks. This may indicate that she was born in the early 1960s, when carbon-14-bound atomic particles from the bomb began to be included in all marine food chains.
After long journeys, Greenland sharks return to the deep, cold waters of the Uummannak Fjord in northwest Greenland (the sharks were part of a large predator tagging and release program in Norway and Greenland).
This suggests that most of our analyzed sharks were actually over 50 years old, Nielsen said.
The scientists then combined the radiocarbon results with estimates of how bowhead sharks grow to create a model that allowed them to test the age of 25 predators born before the 1960s.
Their results showed that the largest shark in the group was a female, measuring over five meters in length. She was most likely about 392 years old, although, as Nielsen notes, the range of possible ages ranged from 272 to 512 years.
Greenland sharks are now the best candidates for the title of the longest-lived vertebrates on our planet, the researcher said with admiration.
Video - Greenland polar shark:
What's more, adult females from the experiment only reach sexual maturity after they grow up to four meters in length. Their first birth occurs only at the age of about 150 years.
Nielsen believes that "future studies should be able to determine age with greater accuracy."
And looking forward to further research:
There are other aspects of the biology of Greenland sharks that are super interesting to know and cover, he concluded.
Recall that earlier scientists have already suggested that every year the Greenland shark grows by 0.5-1 centimeter.
And the reason for longevity, presumably, is a very slow metabolism: this type of shark is - predators live in waters whose temperature ranges from -1 to +5 degrees Celsius.
This also explains the slowness of the shark, for which it was awarded the Latin name Somniosus microcephalus, which means "sleep with a small brain."
The Greenland shark is recognized as the longest living vertebrate animal. The age of a marine predator can reach almost 500 years.
Scientists have concluded that the longest-lived vertebrate known today on the planet is the Greenland shark (Somniosus microcephalus).
It is reported by the BBC.
The researchers came to these conclusions by studying 28 specimens of representatives of the Greenland shark.
To determine the age of the sharks, scientists used the method of radiocarbon dating. They conducted a radiocarbon analysis of the nucleus of the lens of the eyes of sharks and found that the average life expectancy of sharks is approximately 272 years.
Wherein scientists estimated the age of the oldest individual at 392 years.
Also, experts found that Greenland sharks grow extremely slowly - only one centimeter per year, and Greenland sharks reach sexual maturity at 150 years old..
The full results of the study are contained in an article published in the journal Science.
Lead author of the study, Julius Nielsen, a marine biologist at the University of Copenhagen, said: "We assumed we were dealing with an unusual animal, but the fact that sharks were so old came as a surprise to us."
The findings of scientists refuted the ideas of science about the longest-lived vertebrate. Previously, it was believed that such a champion is the bowhead whale, whose age is estimated at 211 years.
The Greenland polar shark, or the small-headed polar shark, or the Atlantic polar shark (lat. Somniosus microcephalus) is a species of the genus of polar sharks of the family of somniose sharks of the catranoid order.
It lives in the waters of the North Atlantic. The range extends further north than other sharks.
Reproduces by ovoviviparity. These slow sharks feed on fish and carrion. They are an object of fishing.
The maximum recorded length is 6.4 m.
The species was first scientifically described in 1801 as Squalus microcephalus. The specific name comes from the Greek words κεφαλή - "head" and μικρός - "small". In 2004, it was established that the previously considered Greenland sharks living in the South Atlantic and the Southern Ocean are an independent species of Somniosus antarcticus.
These are the northernmost and most cold-loving of all sharks. They are widespread in the north of the Atlantic Ocean - off the coast of Greenland, Iceland, Canada (Labrador, New Brunswick, Nunavut, Prince Edward Island), Denmark, Germany, Norway, Russia and the USA (Maine, Massachusetts, North Carolina).
They are found on the continental and insular shelves and in the upper part of the continental slope from the water surface to a depth of 2200 m. In winter in the Arctic and North Atlantic, Greenland sharks are caught in the surf zone, in shallow bays and estuaries near the water surface. In summer, they stay at a depth of 180 to 550 m.
In the lower latitudes (Gulf of Maine and North Sea), these sharks are found on the continental shelf, migrating to shallow waters in spring and autumn. The temperature in their habitats is 0.6–12 °C. Marked in late spring under the ice near Baffin Island, the sharks preferred to stay at depth in the morning, and by noon they would rise to shallow water and spend the night there.
Greenland sharks are top predators. The basis of their diet is fish, such as small sharks, rays, eels, herring, capelin, loaches, cod, sockeye salmon, slingshots, catfish, lumpfish and flounder. However, sometimes they also hunt seals. Tooth marks on the bodies of dead seals off the coast of Sable Island and Nova Scotia suggest that arctic harp sharks are their main winter predators.
On occasion, carrion is also eaten: cases are described when the remains of polar bears and reindeer were found in the stomachs of polar sharks. They are known to be attracted to the water by the smell of rotting meat. They often gather in large numbers around fishing boats.
Greenland sharks are one of the slowest sharks. Their average speed is 1.6 km/h, and the maximum speed is 2.7 km/h, which is half the maximum speed of seals. Therefore, scientists have long wondered how these clumsy fish are able to hunt such fast prey. There is evidence that the polar Greenland sharks lie in wait for sleeping seals.
The Greenland shark is recognized by scientists as the longest-lived vertebrate species. Biologists believe that the animal can live for about 500 years.
In 2010-2013, scientists measured the body length and radiocarbon analysis of the lens of the eye of 28 Greenland sharks. As a result, it turned out that the longest of them (more than five meters) was born 272-512 years ago (the Greenland shark, according to scientists, grows on average one centimeter every year). Such a high life expectancy of sharks is explained by low metabolism, for example, females reach puberty at 150 years old.
TMAO found in the tissues of bowhead sharks helps stabilize enzymes and structural proteins that would not otherwise function properly due to low temperatures and high pressures. Although the temperature of Arctic waters can reach 10 and even 12°C in summer, it can drop to -2°C in the middle of winter. Under such conditions, even the most stable proteins cease to function normally without chemical protection.
As an antifreeze, the body of polar fish produces glycoproteins. Polar sharks accumulate urea and TMAO to prevent ice crystals from forming and to stabilize proteins. At a depth of 2200 meters, the ambient pressure is about 220 atmospheres or 220 kilograms per square centimeter. Not surprisingly, the concentration of the protective substance TMAO is very high in the tissues of the Greenland polar sharks.
Attacks on humans attributed to Greenland sharks are extremely rare. They live in cold waters, where it is almost impossible to meet a person. However, a case was recorded when a Greenland polar shark followed a ship in the Gulf of St. Lawrence. Another shark chased a group of divers and forced them to the surface of the water. Some fishermen believe that the Greenland sharks damage tackle and exterminate fish, and regard them as pests. Therefore, when caught, they cut off the tail fin of the sharks and throw them overboard. Once caught, the Greenland sharks offer little to no resistance.
From the middle of the 19th century until the 60s of the 20th century, the fishermen of Greenland and Iceland caught up to 50,000 bowhead sharks per year. In some countries, fishing continues to this day. Sharks are harvested for liver fat. Raw meat is poisonous due to the high content of urea and TMAO, it causes poisoning not only in humans but also in dogs. This poisoning is accompanied by convulsions and can be fatal.
A traditional Icelandic dish is prepared from the meat of polar sharks through prolonged processing. hakarl. Sometimes these sharks are caught as by-catch when halibut and shrimp are caught. The International Union for Conservation of Nature has given this species a conservation status of Near Threatened.