Sharks are made primarily of cartilage, not bone. Their skeletons consist of cartilage, which is a flexible but strong connective tissue also found in human noses and ears. This cartilaginous skeleton makes sharks lighter and more buoyant compared to bony fish, aiding their swimming efficiency and speed
. In addition to cartilage, sharks have dermal denticles-tiny, tooth-like scales made of dentine and enamel-that cover their skin and help reduce drag while swimming
. Their jaws and certain parts of their skeleton are reinforced with layers of calcium salts called tesserae, which add strength without the weight of bone
. Sharks also have a large, oil-filled liver that contributes to buoyancy since they lack swim bladders typical of bony fish
. In summary, sharks are cartilaginous fish with skeletons made of cartilage reinforced in some areas by calcium deposits, covered with dermal denticles, and supported by an oily liver for buoyancy. Their teeth, unlike their skeleton, are made of hard bone-like material and are continually replaced
