The shark is one of the oldest fauna on earth

The shark is one of the oldest fauna on earth. In their suborder includes about 500 species of different sizes and weight. But they all have a perfect torpedo-like body, keen eyesight and hearing, and catch odors from miles away. the Smell of blood catch at a concentration of 1 mol to 1000000 mol of water. The main weapon of many sharp teeth.In some countries, are commercial species.