Flying fish, belonging to the family Exocoetidae, appear to launch themselves into the air, traversing distances above the waves. This unique locomotion blends aquatic power with aerodynamic principles, prompting the question: do they truly fly like birds, or is their aerial movement something different?
How Flying Fish Take to the Air
Flying fish initiate aerial journeys by building significant speed underwater, typically reaching 35 to 43 miles per hour (56 to 70 kilometers per hour) before breaching the surface. Their streamlined bodies allow for rapid acceleration. As they approach the surface, their powerful tails, particularly the elongated lower lobe of their caudal fin, beat vigorously. This rapid sculling action provides the thrust to launch them clear of the water.
Once airborne, the fish spread their large pectoral fins, which function like wings. Some species, known as “four-winged” flying fish, also extend their pelvic fins for additional lift. These rigid fins create an upward force as air flows over them, allowing the fish to glide. While airborne, they can dip their tail back into the water, rapidly beating it to gain extra thrust and extend their glide distance or make consecutive leaps. Flying fish can reach heights of up to 20 feet (6 meters) and cover distances of 600 to 1,300 feet (180 to 400 meters) in a single glide, with the longest recorded lasting 45 seconds.
The Purpose Behind Their Leaps
The primary reason flying fish take to the air is to escape predators. In the open ocean, where hiding spots are scarce, launching out of the water provides a temporary refuge from aquatic hunters. These underwater threats include tuna, marlin, swordfish, dolphins, sharks, and squid. The sudden aerial maneuver can disorient predators, allowing the flying fish to evade capture.
This aerial strategy serves as a survival mechanism, allowing them to disappear from a predator’s line of sight. While airborne, they can cover significant distances, moving away from immediate danger. However, this evasion tactic is not without risks; once out of the water, flying fish become vulnerable to aerial predators like frigatebirds, gulls, and other seabirds.
Is It True Flight or Something Else?
Despite their name, flying fish do not engage in “true flight” like birds or bats. True flight involves continuous, muscle-powered flapping of wings to generate both lift and thrust, allowing for sustained and controlled aerial movement. Birds, for example, actively beat their wings to stay aloft and propel themselves forward.
Flying fish, conversely, propel themselves from the water with an initial burst of power and then glide using their momentum. Their large pectoral fins function as rigid wings that catch air currents, providing aerodynamic lift but without continuous flapping for propulsion once airborne. This movement is described as gliding, where the fish relies on previously generated speed and air dynamics to travel through the air before returning to the water. Their aerial display is a sophisticated form of gliding, not sustained powered flight.