A shark is a type of fish belonging to the class Chondrichthyes, which includes all cartilaginous fishes. Unlike bony fish, sharks have skeletons made of cartilage, making them more flexible and lighter in water. Sharks are known for their sharp teeth, streamlined bodies, and powerful swimming abilities. They play a crucial role in marine ecosystems as apex predators, helping to maintain the balance of ocean biodiversity. Sharks display various adaptations, including different feeding habits and migratory patterns. While often feared, they are important to ocean health and are currently facing threats from overfishing and habitat destruction.