FACT

Sharks have skeletons made entirely of cartilage, the same flexible material in human ears and noses.

Source: Shark Anatomy - Georgia Aquarium

FACT

Sharks can lose and regrow thousands of teeth in their lifetime, with some species growing new teeth every two weeks.

Source: Shark Teeth Facts - American Museum of Natural History

FACT

Sharks evolved around 400 million years ago, while trees appeared about 350 million years ago.

Source: Shark Evolution Timeline - Smithsonian Ocean

FACT

Sharks first appeared around 400 million years ago, while dinosaurs appeared around 230 million years ago.

Source: Ancient Sharks - Natural History Museum

MYTH

Sharks don't sleep in the traditional sense, but they do have periods of rest and reduced activity.

Source: Do Sharks Sleep? - Discovery Channel