Fish can fly, or so it appears in Season 1, Episode 1 of Life. In the documentary, Attenborough describes how flyingfish can glide forward for over 200 meters, just above the surface of the water, in order to avoid predators. There are approximately 50 species of flyingfish in the family Exocoetidae . These fish do not actually fly; they glide. Gliding is the use of air currents and gravity to move through the air over short distances. Gliding animals often have specific adaptations to allow for intentional control of their trajectories as they fall through the air .
Original descriptions in the scientific literature of the ability of fish to glide date back to the 1930s. Researchers detailed how the the flying fish are masters of many of the aeronautical features of human inventions:
The whirling motor and the whirling propeller, both involving the principle of the wheel, are the essential points by which the airplanes of man differ from flying fishes, nature’s own seaplanes. With this exception, vital it is true, modern airplanes are marvelously close reproductions of flying fishes. To offset this defect in the natural product, the flying fishes are masters of both water and air – submarines and seaplanes in one. — C.L. Hubbs. 1935. Annual Report of the Board of Regents of the Smithsonian .
Where found, flyingfish are a primary food source for larger predatory fish , and it is hypothesized that such gliding is the result of pressure to escape being eaten.
Gliding is not unique to fishes. For example, gliding in vertebrates that live in trees has evolved over thirty times . These terrestrial gliders include mammals, amphibians and reptiles . So, watch out for “flying” snakes!
Image from Nature’s own seaplanes 
(Life, Season 1, Episode 1, starting at approximately 15:32)
by Nicole Gerardo
- Lewallen, EA, Pitman, RL, Kjartanson, SL & NR Lovejoy. 2011. Molecular systematics of flyingfishes (Teleostei: Exocoetidae): evolution in the epipelagic zone. Biological Journal of the Linnaean Society 102: 161–174.
- Dudley R, Byrnes G, Yanoviak SP, Borrell B, Brown RM & JM McGuire. 2007. Gliding and the functional origins of flight: Biomechanical novelty or necessity? Annual Review of Ecology, Evolution and Systematics 38:179–201
- Hubbs, CL. 1935. Nature’s own seaplanes. Annual Report of the Board of Regents of the Smithsonian 333-348.
- Varghese, SP, Somvanshi V.S., John, ME & RS Dalvi. Diet and consumption rates of common dolphinfish, Coryphaena hippurus, in the eastern Arabian Sea. 2013. Journal of Applied Ichthyology 29: 1022–1029
- Rayner JMV. 1988. The evolution of vertebrate flight. Biological Journal of the Linnaean Society 34:269–87.