Sharks are sleek, mysterious and cool. Their streamlined, torpedo-like bodies can reach speeds of up to 60 kilometres/45 miles an hour - that's fast! And, ruling all the world's oceans. But not all sharks are salty - some cruise in freshwater rivers and lakes, too.

And you'll never believe how old these creatures are. They've been around for more than 400 million years! That's at least as old as dinosaurs and definitely older than anyone you know, which means these perfect predators were on earth before humans even existed.

Although you may think of sharks as mean and vicious, like in the movie Jaws, never fear, shark attacks are actually very rare. In fact, sharks are in more danger from us than we are from them. Approximately 100 million sharks are killed each year for food, vitamins, jewelry and other products. Because sharks mature slowly and produce a small number of offspring, their future is endangered by overfishing.

But why should you care? Because as top predators, sharks play a major role in the food chain. When sharks disappear, it throws the whole system off balance.