Oceans cover 70 per cent of the earth surface and whole more that 20,000 species of fish. Of these some 370 species are sharks. Long before dinosaurs existed, sharks roll the waters. They first originated more than 400 million years ago and have changed very little in last 100 million years; today few other species on earth inspire so much respect and fear. These amazing predators sit at the top of the marine food chain by eating out weak and injured. They help maintain a balance equal system. Sharks are highly tuned hunting machines that rely on specialize senses to catch prey. Using their sharp sense of hearing
they can detect sound vibration up to 3,000 feet away. Near the snail, sharks also have tiny gelyfill pores they pick up electrical signals created when animals move. They are especially sensitive to the low frequency pulses from struggling prey. We still have a lot to learn about of these mysterious and misunderstanding creatures, scientist continue to unravel their secrets. When we think of sharks we can't help the think of their teeth. Some species shed as many as 30,000 during their lifetime but replacements always nearby. These teeth point backward to reduce the drag of the water as the shark rises through it. Rows of teeth make it possible for new teeth to rotate in when needed. Water flows through nostrils on the under side of its snail giving the shark a steady steam of all factory information. As a shark goes closer to the catch its sense of smell takes over. Sharks use and loose their teeth all the time. It can detect a single drop of blood in 25 gallons of water. The vibrations from the speaker sound like wounded fish and send these sharks to the frenzy. Many of them are designed to attack but not all of them do, in fact most sharks are harmless to humans.