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Sharks (lat. Selachimorpha) is a superorder of cartilaginous fish comprising eight teams, twenty families and about 350 species. Members of the superorder widely distributed in all seas and oceans, there are also freshwater sharks. Most species belong to the so-called real predators, some species, particularly whale, and giant deep-sea sharks, eat plankton.

For many millions of years before the planet appeared the first man, ruler of the prehistoric seas was a shark. The power of evolution sowed on Earth, countless forms of life that could not stand the severe tests and disappeared one after another, as the shark continued to exist. One prehistoric era is succeeded by another, have any amphibians, reptiles, birds, and mammals – the shark continued to exist. Pterodactyls – the winged reptile for millions of years plied the skies, disappeared from the face of the Earth. Dinosaurs-Triceratops, Brontosaurus, allosaurus and many other “saurus”, it is important chestvovali on our planet died out, leaving no trace. As the shark continued to exist.

About 20 million years ago in the sea scoured a huge Stingray, weighing over 100 pounds, and more than 25 different species of sharks, including sharks, reaching 36 meters in length. The length of these monstrous sharks was Opredelenie their huge teeth. Some of the teeth found in California, weighing 340 grams each and reach 15 centimeters in length, and seven – and ten teeth are quite common. They are triangular in shape and closer to the teeth of modern great white sharks that do not exceed 5-6 inches now with a body length of shark of 12 meters (maximum length). These teeth belonged to the ancestor of the modern great white shark the carcharodon, in huge quantities inhabited the seas. When they were first found in the seventeenth-century scientists, naturalists believed that this fossil bird tongues or teeth of serpents. They could not imagine that this shark’s teeth, and ascribed them to the mythical animal. Continue reading

What sharks are the most dangerous?

About the brutality of the sharks is legendary. People since ancient times afraid of sharks, because sharks of any size can be dangerous. However, among all the sharks you can highlight a dozen of the most dangerous, which can end badly.

Sharks are dangerous not only because they are strong, have sharp teeth and powerful jaws. The main danger lies in the unpredictability of the behavior of toothy predators: despite the fact that the habits of sharks are being studied for a long time, to predict with accuracy how the shark in any given situation, almost impossible.

Dangerous shark species

Today there are more than 450 species of sharks of different sizes, the smallest can reach a length of 17 cm, the biggest is up to 20 meters. But the real danger to humans represent only some species of sharks. Recent years have witnessed the most attacks on humans great white, bull and tiger sharks.

Great white shark

This shark is called “great”: in length it can reach up to 7 meters and weight up to three tons. The mere sight of this blood-thirsty predator is able to inspire terror. If you watched the movie “Jaws”, then you understand what is involved. The reputation of the great white shark is the most grim: in 2012, the year its victims were 11 people, three cases ended in the death of the victims. Continue reading

The most poisonous fishes of Russia

Poisonous fish on the planet much more than poisonous snakes – more than 1250 species (snakes – 410). And every year ichthyologists discover new dangerous species. In this article we are not talking about the exotic inhabitants of the tropical seas, and about ordinary Russian fish living in our rivers. That’s only when you try to use this trivial-looking production in food from fisherman might suddenly begin diarrhea, headache, hallucinations, and other troubles, including death.

Easy Russian fish

Let us first clarify what classes can be divided poisonous fish. So, they are primary and secondary toxic-poisonous. What does it mean? That means there are fish, like snakes produce venom in special glands or by its nature containing in the body dangerous products of metabolism, that is, initially-poisonous.

To secondary poisonous fish are able to accumulate in their bodies a poison contained in the environment. Such environments can be living in the pond poisonous algae or, even worse, fall into the water of toxic human waste.

And if the second paragraph is all clear, and to protect yourself from poisoning very easily (just not enough to catch and certainly not to eat fish caught in suspicious ponds), initially-poisonous things are much more complicated. We begin our story. Continue reading

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Presentation on theme
Sharks (lat. Selachimorpha) is a superorder of cartilaginous fish comprising eight teams, twenty families and about 350 species. Members of the superorder widely distributed in all seas and oceans, there…

Continue reading →