Sharks
In short
Sharks are a group of predatory fish that have skeletons made of cartilage instead of bone. They belong to a class of animals called elasmobranchs, which also includes rays and skates.
In plain words
Unlike most fish, sharks do not have hard bones. Their bodies are flexible because they are made of a tough, bendy material called cartilage. They use gills to breathe underwater and have very sharp teeth for hunting.
A simple example
A Great White shark uses its flexible cartilage skeleton to turn quickly while chasing prey in the ocean.
Why it matters
Sharks are vital for keeping the ocean healthy by controlling the population of other sea creatures. Without them, the entire marine food chain could collapse.
Easy to mix up
People often confuse sharks with rays, but rays are actually close relatives that usually live on the sea floor.