Sharks

ocean · predators · cartilage · ancient

Made of cartilage. Unlike most fish, sharks have no bones at all. Their entire skeleton is made of cartilage, the same bendy material that gives your ears and nose their shape. This makes them lighter and more flexible than fish with hard bones.

Gill slits everywhere. Sharks have five to seven gill slits on each side of their body to breathe underwater. These slits let water flow through and extract oxygen, kind of like how your lungs pull air from the atmosphere.

Bumpy skin armor. A shark's skin is covered in tiny ridges called dermal denticles that look like teeth under a microscope. These bumps reduce drag and help sharks glide through water super smoothly and quietly.

Ancient survivors. The earliest modern sharks appeared around 200 million years ago, during the time of dinosaurs. Some shark-like creatures existed even further back, over 300 million years ago, making sharks some of Earth's most successful animals.

Fins and flippers. Sharks have pectoral fins that work like airplane wings to steer and glide through the water. Unlike most fish, these fins are not attached to their head, giving them amazing control and maneuverability.