Greenland Polar Shark: description, features and interesting facts

The Greenland Polar Shark is the largest representative of the Katrana, belonging to the genus Somniosidae. Refers to cartilaginous fishes, which are not yet widely studied.

Habitat

This is the coldest-loving shark of all family members, preferring a water temperature in the range of 1 to 12 ° C. The area of the Selachia covers the north of the Atlantic Ocean, the Arctic Ocean and includes the Scandinavian countries, the USA, Canada, Russia, Iceland and Germany. The Greenland Polar Shark (somniosus microcephalus) lives in a wide vertical range - from the continental and insular shelf to 2000 m and more. In summer it is most often found at a depth of 200-500 m, and in winter it is closer to the surface. It performs diurnal and seasonal migrations, determined by the movement of plankton and small animals that make up its diet.

Appearance

The Greenland Polar Shark is in sixth place in size after white, reaching 8 meters in length and weighing up to two tons. But the average size of individuals is 4 m, and the weight is 800 kg.

Its body has a streamlined torpedo-like shape. The head is small in size relative to the whole carcass. The mouth of the predator is on the bottom. Jaws are wide and clumsy. The lower one is dotted with blunt square teeth, and the upper one is sparse with sharp teeth. The height of those and others does not exceed 7 mm. Caudal fin of heterocercal type, dorsal - round and small in size.

The body of the Selachium has a color from brown to almost black, sometimes with a greenish tinge. There are dark purple spots all over the body. The eyes of the shark are small, green, without a protective membrane. They are able to glow in the dark, which is explained by the accumulation of bioluminescent copepods, parasitizing on the area around the eyes of this giant.

Features of the structure

The Greenland polar sharks have a large fatty liver, which exceeds 20% of the body weight. This body performs the function of an additional float.

Shark fabrics are highly saturated with ammonia and trimethylamine oxide. Such compounds interfere with the freezing of blood, maintain the working capacity of proteins and the normal course of biological processes in the conditions of the north. Both substances are toxins, therefore shark meat not only has a disgusting taste, but can also lead to poisoning - under the action of gastric juice, trimethylamine oxide is converted to trimethylamine, which causes an alcoholic effect. The urinary bladder is absent in the shark, therefore the products of vital activity are excreted through the skin.

These animals are distinguished by their impressive size and slowness. The speed of its movement is surprisingly small - no more than one kilometer per hour. This is due to the fact that, living in cold waters, most of the energy of the village has to spend on heating its own body. The Greenland Polar Shark is a long-lived animal among the representatives of the animal world. As it is established, the life expectancy of it is up to 500 years.

Food

The large size, low speed of movement and the small mouth of the Selaxia significantly affect what the Greenland polar sharks feed on. She is too slow, cautious and even somewhat cowardly, so most often she watches sleeping, sick or weak seals and, thus, hunts them. The main diet includes organic garbage, carrion and small animals such as cod, flounder, sea bass, octopus, crab, squid, stingray. In the stomachs of these predators, jellyfish, algae, remnants of reindeer and polar bears were found. The smell of rotting meat attracts Greenland sharks, so they can often be found near fishing vessels.

Reproduction

This period falls at the end of spring. Celaxia refers to egg-living animals - it produces eggs deprived of corneal shell size of 8 cm inside itself. For one litter, the Greenland shark produces up to a dozen cubs with a size of at least 90 cm. The females acquire a reproductive capacity when they reach the age of 150 years, their length at that time is 4.5 m, in males it is less - about 3 m.

Interaction with man

The polar (or bowhead) shark is a super-predator. No one hunts for it, the only enemy is a man. These sharks are an object of fishing because of the liver, which people use to get technical fat saturated with vitamins. The Greenland polar shark has been given the status of "Close to a vulnerable position". This species is under close observation of environmental organizations, since the population of sharks is decreasing every year due in part to slow reproduction.

As mentioned above, raw meat from the village is very toxic, due to the high content of urea and TMAO. But the natives of the north learned how to treat it for eating and feeding pets - soaking and boiling allows neutralizing toxins. Icelanders, being descendants of glorious Vikings, prepare from it a traditional dish hakarl. The craft of shark today is engaged in some other countries. It is quite phlegmatic and completely non-aggressive. Surprisingly, such a giant, caught in the network, behaves very quietly. Some fishermen consider these marine inhabitants to be pests - for spoiling gear and destroying fish.

The attacks of polar sharks on humans are extremely rare, because in the cold places where they live, the probability of meeting is very small. However, a case is known when the Greenland polar shark became the reason for the fact that a group of divers had to rise to the surface of the water.

Interesting Facts

To date, according to numerous studies, it is known that the Greenland polar shark is the oldest vertebrate in the world. However, to establish this fact, scientists had to make a lot of efforts. The fact is that most of the methods used to establish the age of the animal are not applicable to the polar shark. It does not form a layer of calcium carbonate in the ears, which determine the age of most fish; The vertebrae of the village are soft, like paraffin, which does not allow you to determine the life span by the growth of the vertebral rings.

The age of polar sharks was determined by the proteins in the center of the lens of the eye. It grows throughout life, and its proteins are formed at the stage of embryonic development. Radiocarbon analysis made it possible to determine the time of their existence in terms of the content of the carbon-14 isotope, the burst of which occurred after the testing of atomic bombs. One of the sharks studied by experts was 392 years old. Taking into account the error of the radiocarbon method of investigation, it is established that polar sharks can live up to 500 years. This longevity is explained by the fact that all vital processes in cold water are more delayed than those of the heat-loving representatives of this family.