A shark’s skeleton is made of cartilage.
Sharks share this lighter skeleton with rays and skates.
A shark’s skeleton is made of cartilage, the tough, flexible tissue also found in parts of our noses and ears. Cartilage is less dense than bone, which helps keep the skeleton light.
Sharks lack the gas-filled swim bladder found in many bony fish. Their light skeletons, oil-rich livers, and lift from swimming help them stay at their chosen depth.