Sharks are very different and widespread literally in all parts of the World Ocean. Now in the world about 450 species of sharks are known. Some types are capable to live in fresh waters. The sizes of sharks, depending on a look, fluctuate over a wide range – from 15-17 cm to 20 m. Bright distinctive feature of these fishes is the structure of their teeth. These they received the popularity and ill fame thanks to several types differing from others in the huge sizes and aggression.
Instruction
1. Sharks – some of the most ancient representatives of family of fishes who are considered besides beings quite primitive. They are predators by nature, and not bad are adapted for such way of life. Many sharks have the fine tool for attack - several hundred sharp teeth which are replaced in process of their exit out of operation, and scaly skin, so rough that a time it is used as an abrasive.
2. The majority of species of sharks as production prefer fish of the average sizes and categorically avoid attack on any larger animals. At the same time the whale and huge sharks who are the largest representatives of family and, in general, the largest fishes – filtration organisms. They generally eat plankton, and sometimes squids and a small small fish. Macrostomatous, huge and whale sharks in a mouth instead of predatory teeth have the "tsedilny device" allowing them to take at once a large number of the small organisms making plankton drifting in the thickness of water near a surface. For this reason large types also live near a water surface. Despite the sizes, they are not dangerous to the person at all, and the whale shark, besides and is good-natured – allows to touch and even to sweep on her astride.
3. A tiger shark – the large predator reaching in length of 5 m, the true dustman of the ocean. She is considered responsible for the majority of attacks on the person. Tiger sharks are very gluttonous and are not picky in food. They eat squids, spiny lobsters, crabs, the most various fishes, two-fold and Gastropoda of mollusks, slopes, sea and migratory birds, sea serpents and turtles whom in this case even the armor cannot save. Attack dolphins and seals. Found parts of crocodiles and pets in stomachs of tiger sharks, and even individuals of the look. They can eat a garbage and drop.
4. A white shark – the predator reaching in length of 6 m. She hunts marine mammals, fish and sea birds. Also attribute her attacks on the person, but it is obvious that people are not among food preferences of a white shark.
5. The Atlantic polar sharks eat sea birds, seals, likod, slopes and kambalovy. Hunt benthonic fishes and animals - a cod, I write, perches, octopuses. Usual production are living closer to the surface of the ocean a pollack, blue whiting, bull-calves, sea chanterelles.
6. Benthonic species of sharks eat Crustacea, polikheta, cuttlefishes, sometimes typically ground fishes - eels, kambaloobrazny. Vida, living in the lower part of the shelf and at depths of 150 - 350 m, eat benthonic Crustacea and fishes - a horse-mackerel, okunevy.
7. The most ancient representative of a sort is the plashchenosny shark more similar to a sea serpent. The Plashchenosny shark reaches in length of 2 m. Lives at a depth up to 1570 m. Eats fish, squids, octopuses and other, smaller species of sharks. Once in a stomach of the caught plashchenosny shark found the Japanese cat's shark which weight reached 560 kg.