1. Stability: The sail provides stability and helps the fish maintain its balance while swimming at high speeds. It acts like a keel on a sailboat, preventing the fish from rolling over.
2. Maneuverability: The sail also aids in maneuverability. It can be raised or lowered to adjust the fish's buoyancy, allowing it to quickly change direction or dive deep into the water.
3. Communication: The sailfish uses its sail for communication with other sailfish. By raising and lowering the sail, the fish can signal its presence to potential mates or warn off potential predators.
4. Camouflage: Some scientists believe that the sail can provide some camouflage by mimicking the appearance of seaweed floating on the water's surface, helping the sailfish blend in with its surroundings and ambush its prey.