Sharks do not have any bones. Their skeletons are made entirely of cartilage, which is a flexible and lighter connective tissue similar to what human ears and noses are made of

. Unlike bony fish, sharks belong to a group called cartilaginous fish (Class Chondrichthyes), which evolved before bony skeletons appeared in vertebrates

. Instead of bones, sharks have a cartilaginous skeleton strengthened in some parts-such as jaws, spinal column, and cartilage around the brain-by calcium salts deposited from their diet, making these areas harder and stronger over time

. Their teeth are the only calcified parts resembling bone, but the rest of their skeleton remains cartilage

. Because cartilage is lighter than bone, it helps sharks stay buoyant and swim faster, compensating for the lack of swim bladders that many bony fish have

. The number of skeletal elements made of cartilage varies by species but typically ranges from about 200 to 400 structures, none of which are true bones

. In summary, sharks have zero bones; their entire skeleton is cartilage- based, which provides flexibility, lightness, and evolutionary advantages in their aquatic environment