Shark is the most dangerous predator of the sea
Shark is the predecessor of the dinosaur. It is 200 million years older than the dinosaurs. At the same time, for 450 million years (the geological age of the shark), these ancient representatives of the fauna have not changed at all.
If we talk about marine life, then fear and hatred in the vast majority of people is caused by only one of them. It's about sharks. These oldest fish on our planet, which appeared about 400 million years ago, pose a number of inexplicable mysteries to researchers. No wonder one of the largest authorities on the underwater world, Jacques Yves Cousteau, said: "The closer we get to know sharks, the less we know about them … you can never predict what a shark will do."
Shark is a collective name. This is the name of a large group of very ancient fish, which includes 350 species. Danger to people, according to scientists, are only 50 of them. However, more pessimistic experts still advise to be wary of any shark whose length is more than 120 cm. In general, the difference in the size of sharks is simply amazing. There are tiny types, the size of a pencil and weighing up to 200 grams; however, the seas and oceans are also plowed by giant sharks, whose length can reach 20 meters and weigh up to 20 tons.
Scientists believe that the sharks that exist in our time were formed as early as 100 million years ago. Jacques Yves Cousteau said to this set: "Through the abyss of centuries, a bloodthirsty, indestructible shark has reached our time, not needing evolution, the most ancient killer has reached, originally armed to fight for existence." Indeed, these "tigers of the seas" are almost ideally suited to attack. Their neck is very mobile; razor-sharp teeth are fixed directly in the gum skin in 4-20 (!) rows and, if necessary, replace each other (a tiger shark “spends” up to 24 thousand teeth in ten years).
Sharks are endowed with a very sensitive sensory system: nerve cells that run from snout to tail form the so-called lateral line; with its help, these predators feel the vibration of water from another animal at a distance of up to 180 meters. In addition, sharks have an amazing sense of smell and can sense blood at a distance of several kilometers. Although, nature still deprived one of this living fossil: they have poor eyesight (they are short-sighted). So they can decide whether to mess with the prey only by getting close enough to it.
The diet of these predators includes almost all living things that are within reach. Sharks have very few natural enemies. For example, sometimes it can be attacked by a killer whale or swordfish, but as a rule, the most ancient inhabitant of the ocean is afraid only of its own relatives. Usually, they are happy to diversify their menu with a weakened or aged friend.
How often does a shark actually attack a person? It turns out not. Although, over the past fifty years, these cases have increased. As you can see, the fact is that every year more and more scuba divers, surfers and diving fans appear in the seas; they, not having the slightest idea about the habits of these predators, often provoke them by their behavior. Nowadays, in a collision with sharks, 15–20 people die every year. Although, many victims could survive with the timely provision of qualified assistance.
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About sharks, we can say that when meeting a person, ancient predators sometimes behave rather strangely: they arch their backs like cats, open their mouths, quickly move their tail, shake their heads and lower their pectoral fins much lower than usual. Sometimes one gets the impression that they take a person for a competitor who encroaches on their hunting territory, and insistently advise him to get away from sin … The fact that sharks do not consider humans food is emphasized by the following circumstances: 3/4 of the victims receive 1-2 blows this predator, after which the aggressor is removed. The wounds show that the giant fish inflicted them only with the upper jaw.
The biggest and scariest looking - and at the same time not dangerous for people! - are whale and giant sharks. Man is not at all interested in these huge creatures. As, however, and other large animals or fish. After all, representatives of both species feed exclusively on plankton and small fish, filtering the water through a kind of giant mesh (more than 15 thousand small, very sharp teeth play its role). The mouth of these sea monsters inspires involuntary respect: 5 adults can easily fit in it …
These giants are constantly moving in search of plankton, covering a distance of thousands of kilometers in one or two months. Representatives of both species are very secretive and try to avoid contact with people. Most of the time, they prefer to stay at considerable depths (1,000–1,500 meters), where darkness reigns and the water is very cold. Only sometimes adult sharks can rise to the surface, while the cubs never leave the depths.
These amazing giant creatures are peaceful and calm; they have no natural enemies. Is that in childhood, when the baby is “only” three meters long, it can be swallowed like a sausage by a sperm whale. While working on research vessels, scientists have repeatedly photographed whale and giant sharks at close range. The sensible giants even allowed themselves to be stroked. Once, German specialists grabbed one of the giants by the tail. The shark looked at the impudent experimenters in a very friendly manner and did not show aggression. The patience of the majestic fish snapped only when one of the scuba divers sat astride it, holding on to the fin. True, even in this situation, the 20-meter giant behaved surprisingly correctly: he did not throw a man, but simply began to slowly sink.
Unlike the huge representatives of living fossils, the white shark (karcharodon) is actually extremely aggressive and dangerous. The white shark usually reaches 5-6 meters in length (the weight of this predator is more than 3 tons), although 12-meter individuals are rarely found. Fortunately for diving enthusiasts, the karcharodon is a rare fish and difficult to encounter. Most often, among the cannibals, the tiger, sand, gray, mako and its relatives, the hammerhead shark and the group of carharin sharks (brown, blue, twilight, lemon, black-fin and white-tip) sharks are also called.
Freshwater predators such as the bull shark that lives in the lakes of Nicaragua and Isabal (Guatemala), the Gangetic shark and "tigers" that are found in the Limpopo and Zambezi rivers are also dangerous to humans. Some experts believe that such fish in the 70-80s of the last century lived in … the Volga! Perhaps they are responsible for the disappearance of fishermen, scuba divers and poachers, and strange scars on the bodies of large sturgeons and belugas. On the banks of the Volga, there are stories of mermaids dragging people under the water and attacking women who rinsed their clothes. Most likely, it was sharks who laid the foundation for the dark stories …
When is the risk of getting to an ancient predator for lunch especially great? It turns out that in order for a shark to attack a person, a number of circumstances are necessary, such as hunger and the absence of "usual" food - fish, octopus or squid. In addition, the water temperature must be at least 20 degrees Celsius, otherwise the shark stops feeding altogether. But what else affects the mood of the prehistoric predator is unknown. In addition, they sometimes show extreme aggressiveness even at a water temperature of only 13 degrees …
It is known about sharks that they can attack people both at depth and 10-50 meters from the coast. What is causing this is not entirely clear. Most likely, the abuse of fishing forces sharks to look for additional sources of food. In addition, supporters of scuba diving often ignore the warnings of the authorities and go straight to the habitat of ancient predators. So the latter do not hunt people, but come across them during the hunt by accident. Unfortunately, as a rule, such contacts end badly for careless divers …
Much is known about shark attacks on humans. Dark stories are readily published, and films about the atrocities of these ocean dwellers are popular. But who knows if there are stories among the sharks themselves about aggressive human predators? At least such "horror stories" would have a completely legitimate basis. Indeed, in a number of countries for a long time there has been a constant fishing for these creatures.
Meat of living fossils (especially the fins of soup sharks) is considered a valuable and useful food product; the liver, rich in fat and high in vitamins, has found widespread use; bags and other haberdashery are sewn from shark skin, moreover, it is needed in the manufacture of felt (soft fleece is made with special brushes from the skin of ancient fish); their teeth are used as souvenirs. In general, a person uses the captured predator almost entirely.
However, very often the fins of a living predator are cut off and left to die slowly and painfully in the sea. The fishery at times takes on such a scale that the number of these ocean dwellers off the coast of a number of countries has begun to dramatically decrease. Because of this, the authorities are forced to introduce a complete or partial ban on the capture of these ancient creatures. And yet, some species are nowadays destroyed by 80–90%.
In general, the shark is unique. For example, being a fish, it can calmly … drown! In order to avoid this unenviable fate, this ancient fish must be constantly in motion, opening its mouth. This is the only way it can capture and pass through the gills the volume of water necessary for normal breathing (the jaw muscles intended for "pumping" are poorly developed in a shark). So they can rest for no more than an hour. With a longer stop, these predators die from suffocation.
In addition, the shark does not have a swim bladder and, despite the large fat-saturated liver (its weight is 1/5 of the weight of the whole body), they are deprived of the so-called neutral buoyancy. Therefore, when the movement stops, the shark does not "hang" in the water, but slowly goes to the bottom, that is, it drowns …
But, as you know, there are no rules without exception. For example, a sand shark is able to swallow air and keep it in the stomach, providing itself with buoyancy for several hours. Other members of this family also have the ability to stop and "meditate." True, only in some places. In the Caribbean Sea, off the coast of Mexico, extensive grottoes with several exits were discovered relatively recently. There are springs of fresh water at their bottom. Here are the real "bedrooms" or "beauty salons" of ancient monsters.
Living fossils spend several days in these caves; the current there is weak, and they lie on the bottom, after which they fall into a daze. Although sharks do not sleep in the full sense of the word and continue to observe living creatures, they are not aggressive and practically do not move. All physiological functions of their body slow down dramatically. Not all predators enter the grottoes. It is possible to find representatives of only a few species there: nurse shark, bull shark, Caribbean shark, sand shark and (very rarely) blue shark.
Why these predators choose this type of recreation is unknown. According to one version, they heal wounds in a calm place, recover from illness, or simply get rid of external parasites that cannot live in desalinated water. Sharks, who have fallen into blissful rest, are "cleaned" by their "freeloaders" - sticking fish.
Another feature of the body of sharks lies in the fact that they do not have a strong bone skeleton, which in these inhabitants of the ocean is replaced by a cartilaginous one. Sharks' eyes are protected by a blinking membrane, which drops down before attack. In some species of these creatures, the eyes can turn inward at all! It is also curious that sharks are the only living creature that, for unknown reasons, does not get cancer.
They do not have a constant body temperature: it is close to the ambient temperature. But some representatives of these creatures can "warm up" their muscle tissue with the help of blood vessels-heat exchangers. After all, warm muscles are more effective during hunting than cold ones!
By the way, these monsters are surprisingly gluttonous and absolutely not picky about food. Shark stomachs can stretch, increasing several times; sometimes completely unexpected objects are found in them. For example, a shark killed near a pier in Australia managed to "dine" with half a ham, a ram, a bulldog (!) And … a ship's scraper. And her relative, who was caught in the Adriatic Sea, was seduced by three coats, a raincoat and a car number.
Because sharks do not need food every day, strange fish can store food. In this case, nature has endowed them with a kind of "extra" stomach, where the contents can be stored without spoiling, from 10 days to a month. What contributes to such a high-quality "conservation", scientists cannot say. When the monster is thoroughly hungry, it "transfers" the stored provisions to the main stomach. If the shark has used up its supply of "canned food", it rushes at everything that gets in the way. Once a short-sighted predator managed to "bite" even … with a depth charge of delayed action! True, this meal was the last in his life …
To this day, it is not clear how sharks adapt to life in fresh water in a short time. In general, they often puzzle scientists. Shark survivability has become the talk of the town. Repeatedly the fishermen, inadvertently approaching this aggressor, who did not show signs of life for a long time, received serious injuries: the "dead" fish strove to grab them with their teeth. There are also known cases when people lost their limbs when approaching … a gutted shark! A few centuries ago, a kind of "revolution" took place in the ocean: blue, whitetip and silk sharks, which had been playing a secondary role for more than nine million years, rapidly ousted the former owners of the watery expanses - mako and white sharks. Why? There is no answer, as you can imagine.
And one more mystery: somehow a 70-centimeter female shark got into the Bavarian Sea Star aquarium, which cannot be attributed to any of the known species. The mysterious creature actually does not know how to swim (instead it bounces in the water), it has huge teeth and hair. The position of the predator's eyes is also atypical. In addition, it can fold its fins, as whales do. None of the experts was able to determine the species of the mysterious fish.
So, these ancient predators are still the most mysterious creatures that live in the ocean. But our era may be the last for a living fossil. It seems that the terrible sea monster will have time to go into oblivion before science can unravel all of its secrets. And will he be able to?
V. Syadro
