This streamlined, cylindrical body shape reduces drag and requires a minimum of energy to swim. The dark top of the countershaded shark blends in with the dark ocean depths when viewed from above. The light bottom blends in with the lighter surface of the sea when viewed from below. As a result, predators or prey do not see a contrast between the countershaded shark and the environment. FINS Shark fins are rigid, supported by cartilagenous rods and proteinaceous fibers.
Sharks have five different kinds of fins.
Paired pectoral fins lift the shark as it swims. Paired pelvic fins as well as one or two dorsal fins stabilize the shark. In some species, dorsal fins have spines. A single anal fin provides stability in some species where it is present. The caudal or tail fin propels the shark.