Sharks do not have any bones. Instead of a bony skeleton, sharks have a skeleton made entirely of cartilage, the same flexible and lighter material found in human ears and the tip of the nose. The number of cartilaginous structures in sharks varies by species but generally ranges from about 200 to 400. Their jaws, spinal column, and braincase are reinforced with calcium salts, making these areas harder, but these are still not bones. The only hard parts sharks have that resemble bones are their teeth, which are mineralized and fossilize well. This cartilaginous skeleton gives sharks a lighter body, aiding buoyancy since they do not have swim bladders like bony fish, and provides flexibility and speed advantages in swimming. In summary, sharks have zero bones but have hundreds of cartilage structures instead.