Greenland polar shark: description, features and interesting facts. Life of the Greenland Shark Norwegian Shark
Greenland polar shark, or small-headed polar shark, or Atlantic polar shark (lat. Somniosus microcephalus) - belongs to the family of straight-mouthed sharks.
If for most sharks the acceptable ocean water temperature starts at +18 degrees, then polar sharks have chosen truly cold waters where the temperature does not exceed -2 to +7 degrees. But how is this even possible - after all, sharks are extremely thermophilic, even those whose bodies are capable of raising the temperature above the temperature of the surrounding water?
First, about the Arctic sharks themselves. The most famous representative among the genus Somniosidae is the Atlantic (aka Greenland, aka small-headed) polar shark (Somniosus microcephalus). Its permanent habitat is the northwestern coast of Europe and the coast of Greenland; sometimes it can be found off the northern coast of Russia.
Externally, this fish is very similar to a torpedo, and its dorsal fins, which have become the hallmark of sharks, are small in size. It is these sharks that live longer than all others - about 100-200 years! The polar shark has become a long-liver due to the slow progression of all life processes in its body. It grows very slowly: an individual of such a shark was kept in a scientific institute, where it was studied for a long time - in 16 years the predator grew only 8 cm.
The predator has the largest liver among all other sharks, it reaches 20% of its total weight - because of this organ, about 30 thousand individuals were annually caught on polar sharks for centuries, and industrial fat was melted from the liver. Fishing for this fish is not interesting for sports fishermen - there is practically no struggle; after the predator is brought to the surface of the ocean, it rises into the boat just as if it were a log.
The polar shark does not swim away from Arctic waters; in summer it stays at a depth of 500-2000 meters, and winters at the surface of the ocean - the water temperature here is higher.
It feeds on any local living creatures, be it fish or pinnipeds, and also attacks unwary animals caught in the water. For a long time, this shark was considered a carrion eater: it is always slow, so this fish is often called sleepy - where can it keep up with its prey! However, in 2008, Keith Kovacs, an ichthyologist at the Norwegian Polar Institute in Troms, discovered the bones of a polar bear, eaten "fresh" by the fish, in the stomach of a captured polar shark. This find was the subject of a serious debate among scientists - could a polar shark attack and kill a polar bear?
Theoretically, an adult predator is quite capable of drowning a bear, because her height and weight are twice as large - 6 meters and 1,000 kg, respectively. And yet, according to scientist Vince Gallucci of the University of Washington and Jeffrey Gallant, a Canadian marine predator researcher, the Arctic shark will not take such a risk - an attack on a large predator with impressive fangs and claws.
She is quite content with easier prey, hunting for which does not involve the risk of injury. Gallucci believes that the bear drowned himself, and the shark discovered his body and feasted. On the other hand, in the legends of the indigenous inhabitants of Greenland - the Inuit Eskimos - there are stories about arctic sharks attacking kayaks and caribou who dared to come close to ice holes.
The polar shark ranks sixth in size among other species of predators.
The size of animals at birth is approximately 38 cm, maturity is reached when males reach a length of 3-3.5 m, females - 4-5 m. The maximum length of a shark is 8m. Like other sharks, this species is viviparous.
In terms of aggressiveness, this species is not far from the whale shark.
The teeth of this predator are small - their length does not exceed 7 mm, the upper ones are needle-shaped, the lower ones are strongly curved. The mouth itself is small and cannot open wide.
There is no unanimous opinion among ichthyologists about the reproduction of polar sharks. Some sources indicate that this fish is viviparous, with a litter of up to 10 sharks about 1 meter long.
According to other sources, the polar shark reproduces in the spring, laying up to 500 oval eggs at depth. These eggs are quite large (up to 8 cm in diameter) and do not have a protective cornea. The eggs hatch into polar shark fry. Time will apparently tell which scientist is right.
But the most dangerous enemy for the polar shark is man. It is he who can threaten the extinction of any species of living beings on the planet, as often happens.
And finally, how does the polar shark survive in the icy waters of the Arctic?
And she succeeds in this because among the organs of her body there are no kidneys or urine-excreting pathways - the removal of ammonia and urea occurs through the skin of the predator. Therefore, the muscle tissue of a shark contains large quantities of nitrogen trimethylamine, which is also a “natural antifreeze” (osmolyte), which prevents the predator’s body from freezing even at subzero temperatures.
It is known that trimethylamine, contained in fresh polar shark meat, causes an effect similar to intoxication in dogs that eat it - the dogs cannot rise to their paws for some time. By the way, the Eskimos of Greenland call a drunk person a “sick shark.” Most likely, it is precisely because of the nitrogen content of trimethylamine in the body that the polar shark is so slow.
The meat of these sharks can be eaten if it is kept in the sun for several months, placed in a natural glacier for about six months, or boiled in repeatedly changed water. The Icelandic national dish, hakarl, is prepared from shark meat.
Scientific classification
Kingdom: Animals
Type: Chordates
Class: Cartilaginous fish
Squad: Katraniformes
Family: Somniosidae
Genus: Arctic sharks
View: Arctic shark (Somniosus microcephalus)
Scientists have caught a shark in the North Atlantic that was born, according to some estimates, in 1505. Having determined the age of the fish using radiocarbon dating, they announced that this “old lady” may be the absolute record holder for life expectancy among vertebrates.
This shark is a species of Greenland, or arctic, shark that grows throughout its life, adding approximately 1 cm per year. The fact that some of them reach sizes of more than five meters indicates the enormous life expectancy of these fish. But it was only now possible to verify this.
They have learned to determine the age of sharks using radiocarbon dating. Scientists conducted radiocarbon dating of the nucleus of the lens of sharks' eyes.
Marine biologist Julius Nielsen from the University of Copenhagen discovered that the 5.4-metre Greenland shark his team studied was at least 272 years older than thought. She is already more than 512 years old.
The animal was found several months ago. The shark's potential age was determined in a study by the Arctic University of Norway, published in the journal Science. The shark may have been born in 1505, making it older than Shakespeare. Scientists are testing 28 other sharks of this species, all of which may also be long-lived.
These massive, slow-moving predators live in the cold waters of the Arctic Ocean and the North Atlantic. They reach sexual maturity at the “tender age” of 150 years.
Scientists attribute the longevity of this shark species to a very sluggish metabolism, as well as low environmental temperatures. Recent research has shown that cold environments can help slow down aging, and these centuries-old sharks are certainly proof of that.
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, there was a recorded case in which a Greenland 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 Greenland sharks damage gear and destroy fish, and regard them as pests. Therefore, when caught, they cut off the tail fin of the sharks and throw them overboard. Once caught, Greenland sharks offer virtually no resistance.
These Arctic centenarians are a kind of “time capsule”, and studying them can provide insight into the extent of the impact of human civilization on the oceans.
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Greenland shark, or smallhead arctic shark, or atlantic polar shark(lat. Somniosus microcephalus) - a species of the genus of polar sharks of the family of somniosa sharks of the order Katraniformes. Lives in the waters of the North Atlantic. The range extends further north than that of other sharks. It reproduces by ovoviviparity. These slow-moving sharks feed on fish and carrion. They are objects of fishing. Maximum recorded length 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 determined that previously thought to be Greenland sharks, which live in the South Atlantic and Southern Ocean, are a separate species Somniosus antarcticus .
These are the northernmost and most cold-loving of all sharks. They are widespread in the north 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 island shelves and in the upper part of the continental slope from the surface of the water to a depth of 2200 m. In winter, in the Arctic and North Atlantic, Greenland sharks are found in the surf zone, in shallow bays and river mouths near the surface of the water. In summer they stay at depths of 180 to 550 m. In 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. Sharks tagged under the ice off Baffin Island at the end of spring preferred to stay in the depths in the morning, and by noon they rose to shallow water and spent the night there.
The maximum recorded length is 6.4 m and the mass is approximately 1 ton. The largest individuals can reach 7.3 m and weigh up to 1.5 tons. However, on average, the length of these sharks ranges from 2.44-4.8 m, and the weight does not exceed 400 kg.
The head is elongated; the distance from the tip of the snout to the pectoral fins of the 2.99 m long shark was 23% of the total size. The snout is short and rounded. The massive body has the shape of a cylinder. There are no spines at the base of both dorsal fins. The dorsal fins are small and of equal size. The base of the first dorsal fin is located closer to the pelvic fins than to the pectoral fins. The distance between the dorsal fins exceeds the distance between the tip of the snout and the second gill slit. There are no lateral carinae on the caudal peduncle. The caudal peduncle is short. The distance between the bases of the second dorsal and caudal fin is less than twice the length of the base of the second dorsal fin.
The gill slits are very small for a shark of this size. Color ranges from pale gray-cream to black-brown. As a rule, it is uniform, but there may be white spots or dark stripes on the back. The upper and lower teeth are very different: the lower ones are wide, with a large flattened root and apexes strongly beveled towards the corners of the mouth; the upper ones are narrow and symmetrical.
The scientists' analysis showed that the average life expectancy of Greenland sharks reaches at least 272 years, which makes them the longest-living record among vertebrates. Researchers estimated the age of the largest shark (502 centimeters long) at 392 ± 120 years, and individuals whose size was less than 300 centimeters turned out to be younger than a hundred years.
Greenland sharks are apex predators. The mainstay of their diet consists of fish such as small sharks, rays, eels, herring, capelin, loaches, cod, groupers, catfish, lumpfish and flounder. However, they sometimes also hunt seals. Teeth marks on the bodies of dead seals off the coast of Sable Island and Nova Scotia suggest that Arctic Greenland sharks are their main predators in winter. On occasion, they also eat carrion: 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 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 their maximum speed is 2.7 km/h, which is half the maximum speed of seals. Therefore, scientists have long been surprised at how these clumsy fish are able to hunt such fast prey. There is evidence that Arctic Greenland sharks lie in wait for sleeping seals.
The Greenland shark is recognized by scientists as the longest-living species of vertebrate (previously the bowhead whale was considered such). Biologists believe that the animal can live about 500 years. In 2010-2013, scientists measured the body length and radiocarbon dating of the eye lens 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 by one centimeter every year). Such a high life expectancy of sharks is explained by low metabolism - for example, females reach sexual maturity at 150 years.
Greenland sharks reach sexual maturity at approximately 150 years of age. Females mature at a body length of 450 cm, and males at a body length of 300 cm. Greenland sharks are ovoviviparous. The breeding season is in summer. The female bears about 500 soft ellipsoidal eggs. The eggs are about 8 cm long and lack a horny capsule. There are about 10 newborns in the litter, 90 cm long.
From the mid-19th century until the 1960s, fishermen in Greenland and Iceland caught up to 50,000 Greenland sharks per year. In some countries, fishing continues to this day. Sharks are hunted for their liver oil. Raw meat is poisonous due to its high urea and trimethylamine oxide content; it causes poisoning not only in people, but also in dogs. This poisoning is accompanied by convulsions and can lead to death. The traditional Icelandic dish hakarl is prepared from the meat of polar sharks through long-term processing. Sometimes these sharks are caught as by-catch during the harvest of Sedna, who went into the depths, where she became a goddess, and each of her cut off fingers turned into some kind of sea animal, including the Greenland polar shark. The shark was tasked with avenging Sedna and one day, when the girl’s father was fishing, she overturned the kayak and ate him. When an Eskimo dies in this manner, the natives say that Sedna sent the shark
The polar shark belongs to the category of little-studied cartilaginous fish. Knowledge about her is insignificant. This is primarily due to the fact that the fish lives in harsh, cold waters, and besides, prefers to spend most of its life at depth. This is a predator. You can meet it in the White Sea, in the southern regions of the Barents Sea and in the waters of the Pechora Sea. Sometimes the fish migrates further east and ends up in the Kara Sea. She is a frequent visitor to the coast of Greenland, constantly lives in the coastal waters of northern Norway and is very fond of the waters of Iceland. It is also often found in the Baffin Sea and Hudson Strait.
Appearance
In terms of size, the polar shark successfully competes with the white shark. The length of her body reaches 6.5-7 meters. Weight fluctuates within a ton. There are specimens weighing up to 2 tons. Basically, the fish is 3-4 meters long and weighs no more than 800 kg. As for ferocity, here the predator is significantly inferior to its aggressive brothers. The body of the fish has an elegant, streamlined shape and is very similar to a torpedo.
The color of the skin can be dark green or brown. The entire carcass, from nose to tail, is strewn with small black and purple spots. The head, relative to the size of the body, is small. The shark's jaws are wide. The upper one has small, sharp and sparse teeth. On the lower jaw, the teeth grow much more densely, but they do not taper towards the top, but are square and blunt. The caudal fin, like that of most selachians, is asymmetrical in shape. Its upper part is larger than the lower part.
Reproduction and lifespan
This shark breeds in the spring. She lays several hundred eggs at a depth. The eggs are oval shaped and quite large. Their size reaches 8 cm. It is noteworthy that they do not have a protective cornea. These predatory fish live for about 40-50 years. The life expectancy of females is 10 years longer than that of males.
Behavior and nutrition
In summer, the polar shark prefers to be at great depths. This is a water column from 500 to 1000 meters from the surface. Here it eats fish and invertebrates. It also feeds on carrion. The corpses of seals, walruses, and whales are its constant diet. It has not been observed to attack large living mammals. The fish is too cowardly, cautious and slow to allow itself to fight with a strong and fast animal. History also knows no cases of polar shark attacks on humans. In winter, it moves from the depths to the upper layers of water. At the same time, its diet does not change in any way, but this fish becomes available for catching.
Enemies
The main and perhaps the only enemy is man. The polar shark has a very large liver. Because of it, fish are caught, producing technical fat rich in vitamins from this organ. Predator meat is poisonous. This selachia does not have a bladder, and accordingly there is no urinary tract. Waste is excreted from the body directly through the skin. Local peoples who regularly catch polar sharks have learned to eat their meat. They soak it, boil it in several waters and only then consume it as food. Unprocessed meat has a strong alcoholic effect and a disgusting taste.
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The polar shark is a cartilaginous fish that science has not studied very well. There is very little official information about this species.
This is due to the fact that polar sharks live in harsh waters, and at considerable depths.
These predators are found in the White Sea, in the southern waters of the Pechersk and Barents seas. Some individuals migrate further east and end up in the Kara Sea. Arctic sharks are often found off the coast of Greenland, Norway and Iceland. In addition, representatives of the species live in the Hudson Strait and the Baffin Sea.
Shark appearance
These cartilaginous fish are almost as large in size as white fish. The body length of the polar shark varies between 6.5-7 meters.
Individuals weigh about a ton, but there are specimens whose weight reaches 2 tons. The average length of a polar shark is 3-4 meters, and the average weight is 800 kilograms.
If we talk about aggressiveness, then these sharks are significantly inferior to their counterparts. The polar shark's body has a perfectly streamlined shape, reminiscent of a torpedo.
The color can be brown or dark green. The entire body is covered with small black-violet spots. The head, in comparison with the size of the whole body, is not large. The jaws are wide. The teeth on the upper and lower jaws are different. In the upper jaw they are sharp and sparse, but in the lower jaw they have a blunt square shape and are set much denser. The caudal fin has an asymmetrical shape: its upper part is much larger than the lower.
Shark behavior and nutrition
In summer, these predators prefer to stay at great depths - approximately 500-1000 meters. At this depth, sharks hunt invertebrates and fish. In addition, the diet includes carrion: corpses, .
There have been no recorded cases of polar sharks attacking large mammals. These predators are too slow, and also cowardly, so they do not fight with tougher and stronger animals. Also, in history there are no recorded cases of polar shark attacks on people.
In winter, these predatory fish rise from the depths to the upper layers of water. At the same time, the predator’s diet remains unchanged. During this period, polar sharks become available for fishing.
Arctic sharks are inhabitants of cold northern waters. Reproduction and lifespan
The breeding season occurs in spring. Arctic sharks lay several hundred eggs in the depths. The eggs are quite large, their length is approximately 8 centimeters, they have an oval shape. Eggs do not have a protective cornea.
The lifespan of polar sharks is approximately 400-500 years, with females living on average 10 years longer than males.
The main enemy of the polar shark is man. Enemies of the polar shark
The most basic and, probably, the only enemy of the polar shark is man. This fish has a very large liver, and it is because of the liver that these fish are caught. Technical fat is made from it. The meat of polar sharks is poisonous. This is because they do not have a bladder or urinary tract, and all body waste is excreted through the skin.
