Sharks are some of Earth's ultimate survivors. They are among the oldest creatures on the planet, predating dinosaurs and trees and surviving multiple mass extinctions. They're also hugely diverse, with more than 500 modern species swimming the world's oceans, from little fish the size of your hand up to 60 foot (18 meters) giants.
Sharks play a critical role in ocean ecosystems, and they're found in all of Earth's oceans. But many species are now under threat from climate change, overfishing, pollution and the shark fin trade.
