Scientists believe that the denticles are used to cut the victim if it's eyesight is failing or it's dark. Once the shark cuts the victim, the blood gives off a more accurate position on the prey. The shark can then home in on the wounded animal and make it's initial strike. One is shape. The normal fish is not as broad shaped in the frontal area.
Sharks have broad heads and oversized mouths evolved for eating.
Their tail fins are not identical in shape to each other. The upper fin is bigger in size and shape than the lower fin. Another difference lies inside the jaws. The fish has teeth used for grasping prey. The shark however has larger, more broad teeth used for shredding and tearing meat.