:A dolphin’s dorsal fin has two, main functions: stability and thermoregulation. The fin acts similarly to the keel of a sailboat, helping the dolphin swim through the water in a straight line. The dorsal fin is primarily composed of cartilaginous tissue and lacks blubber. Therefore, it is often used as a “thermal window”, allowing dolphins to dump excess heat to their environment when their internal body temperature gets too high. Like a human fingerprint, there are no two dorsal fins that are exactly identical. Each has its own unique shape, height, thickness, and notches. Scientists utilize the appearance of dorsal fins to identify individuals in the wild. Many populations are extensively catalogued by dorsal fin photographs, which allow scientists to study specific groups of resident dolphins for many years.