How Do Flying Fishes “Fly?” Well, Actually, They Glide.

Why do flying fishes fly? To escape predators, to flee from surprises like boat engines next them, perhaps to entertain you during the ride to a dive site. In any event, they earn their names by propelling themselves out of the water and gliding for long distances on broad pectoral fins.

Torpedo-shaped and silvery, sometimes with markings in subdued colors, they’re not especially exotic visually. But they’re impressive both underwater and in the air.

flying fish takeoff — *Beating their tails back and forth as they break the surface, flying fishes add speed to their takeoffs, leaving behind wiggly lines in the water.*

YOU’RE UNLIKELY TO SPOT ANY FLYING FISHES WHILE DIVING ON THE REEF but you might well see them sailing along beside your boat during the ride to the dive on the reef. And, yes, these open-ocean denizens do fly – in the form of lengthy glides through the air. And they do it well enough to attract the interest of engineers as to their aerodynamic qualities.

IN AIR & SEA

Flying fishes, more than 40 species in Family Exocoetidae, are open-water, fishes found in oceans worldwide, mostly in tropical and semi-tropical regions. They’re superbly equipped to be fast swimmers under the surface and long-term gliders above it.

Streamlined bodies serve them well for speedy swimming and for propelling them into fast lift-offs into the atmosphere.
Bird-wing-like pectoral fins help them hang in there for long glides.
Coming down, their unevenly forked tail fins help them bounce on the surface into new glides.
Rigid backbones and other body parts help them stay streamlined in the air and deal with the force of crashing back under the ocean surface.
Some species accomplish greater stability and longer flights with enhanced pelvic fins behind their pectorals – “four-winged” flying fishes.

WHY DO FLYING FISHES FLY?

Mostly, they fly to escape predators, of which there are a lot. These include mackerels, tunas, swordfish, marlin, porpoises, squids and other piscivores, fast swimmers in their own right.

Exocoetidae "wings" — *A researcher at the U.S.’s National Marine Fisheries Services displays the broad pectoral fins of a flying fish, species not stated.*

An airborne escape gives them a secret weapon – the ability to instantly disappear from their pursuers in an unknown direction and distance. And they can do so airborne at a faster rate than underwater. Unfortunately, it also means they’re at risk of in-air predation by seabirds during their time above water.

For their own part, flying fishes are generally described as omnivores, willing to eat anything that comes their way. Mostly, they’re planktivores, taking in zooplankton, primarily small crustaceans like copepods, as they zoom through the water.

HOW DO FLYING FISHES FLY?

To be clear, flying fishes aren’t able to engage in powered flight. They’re strictly gliders that achieve a long in-air trajectory that starts with powerful underwater tail action that sends them up to 35 miles per hour before takeoff.

To initiate lift-off from underwater, they coil their bodies in a “C” shape and propel themselves forward. On the surface, with tails whose lower lobes are longer than their upper sections, they flick their tails, against the water, producing a wiggly line.

*A sailfin flying fish (Parexocoetus brachypterus) sketched for a 1903 catalog of marine fauna in the Hawaiian Islands.*

As they start to break the surface, the rapid back-and-forth tail action enhances their velocity. Spreading their fins, they achieve heights of as much as 20 feet, speeds up to 40 miles an hour. They glide in gentle arcs that have been known to stretch more than 600 feet.

HOW DO FLYING FISHES FLY? – FLIGHT PLANS

One key to how flying fishes fly so successfully is that, like birds, they also take advantage of updrafts to enhance their flight paths, in the fishy fliers’ cases, updrafts associated with the leading edges of waves.

As they arc back toward the sea, they can beat their tails on the watery surface to relaunch their flights for another glide. Some have been recorded using consecutive glides to extend their flights to more than 1,200 feet.

Returning to the water, they fold their fins back and assume the torpedo-shape that facilitates fast swimming. A flying fish near Japan holds the record for a flight lasting 45 seconds.

flying fish anatomy — A sketch illustrates a prototypical flying fish’s anatomy, including broad pectoral wings and an unevenly notched tail with a longer lower lobe, In ‘”four-winged” flying fishes, the pelvic wings are also enlarged, aiding in flight duration.

HOW DO FLYING FISHES FLY? – AERODYNAMICS

After reading his children a book that talked about the fishy fliers, a Seoul National University engineer named Haecheon Choi became so interested in them that he and a colleague decided to investigate how they did it. Their curiosity was good for science but bad for the fishes they obtained, which were dried and stuffed with their fins extended for aerodynamic research in a wind tunnel.

They found the fishes’ lift-to-drag ratios compares well with those of birds like teals and wood ducks. And the ratio (and distances) were greatest when the fish glided parallel to the surface, as they optimally do in the real world. And, they found, gliding along close to the ocean surface appeared to improve their ratio.

HOW DO FLYING FISHES FLY? – HYDRODYNAMICS

As a graduate mechanical engineering student at the Georgia Institute of Technology, Patricia Yang took a different approach. In research conducted in Taiwan, she focused on the fishes’ in-water technique as they prepared to launch themselves from ocean to air. Working with juveniles, she and her colleagues used high-speed video to monitor the speed and angle with which their subjects broke the surface – a formidable challenge for juveniles.

They found that in less than a second the little fishes accelerated to four to five times the earth’s gravity. Once in the air, they achieved gliding speeds as fast as 3.3 ft/1.3 m per second – 10 times faster moving through the air than underwater.

*A band-wing flying fish (Cheilopogon exsiliens), a denizen of the Atlantic basin found from Cape Cod to Brazil.*

HOW DO FLYING FISHES FLY? – BASICS

Flying fishes are found in oceans worldwide, predominately in tropical and semitropical waters. They are a pelagic (open water) fishes, most commonly found in the epipelagic zone – that is, the top layer of ocean.
But some tropical species, like the ones that race your boats on the way to dive sites, reside in waters off but near coral reefs.
Estimates of the numbers of species vary significantly among sources, from 40 to more than 65.
Depending on their species, they can be a long as 18 inches, but more typically are in the 7-12 in/17-30 cm range.
Most species reproduce through seeking out bits of flotsom, like sargasso seaweed, in which they can create nests, females laying eggs for male fertilization. Some species reproduce through broadcast spawning, spewing eggs and sperm in the waters for fertilization and dispersal of resulting larvae through the currents.

HOW DO FLYING FISHES FLY? – FISHY FLIER ERRATA

It’s not unknown for the fishy missiles to land in boats as an unfortunate consequence of their speedy glides. You occasionally read or hear stories of them hitting passengers on the boats in the process, with injurious results.
The fishes’ scientific family name, Exocoetidae, derives from Greek words meaning “sleeping outside” and “resting place.” They were believed to leap out of the water to sleep on land. Also, landing in boats had something to do with it.

flying fish ancient art — *A modern-day artist’s recreation of an ancient Minoan fresco found during early 20th Century excavations on the Greek Island of Milos.*

The French-made Exocet missile was named for the flying fish – Exocet is the French word for them. The anti-ship missile was designed to fly just above the ocean’s surface, with one model launched underwater from a submarine.
The Caribbean island of Barbados traditionally bills itself as “the land of the flying fish” due to its one-time abundance in the surrounding seas.
In Barbados, fried or steamed flying fish is traditionally served as a complement to a cornmeal dish called cou-cou and the two together are considered the island’s national dish. Unfortunately, due to overfishing, they’re somewhat scarce in the region’s seas at present.
Besides Barbados, the fishes are commercially fished in China, Japan, India, Indonesia and Vietnam.
Flying fishes are attracted to lights and in some places the fishes are netted as they flock to torches or lights held by fishermen on dark nights.
In some Pacific cultures, an ingenious fishing technique has been to partially fill a canoe with water, suspend a lantern over it and leave it overnight. In the morning the water in the canoe is awash with fishes that have leapt into it.

PRINCIPAL SOURCES: Marine Biology, Peter Castro, Michael Huber; Marine Life, Caribbean, Bahamas, Florida, Marty Snyderman & Clay Wiseman; Encyclopedia of Fishes, John Paxton and William Eschmeyer; Reef Fish Identification Florida, Caribbean, Bahamas, Paul Humann, Ned DeLoach; Flying Fish, National Wildlife Federation; Flying Fish, National Geographic; Flying Fish: Missiles of the Sea, Loyola University of New Orleans; Why fish jump and how they do it, ABC News (Australian Broadcasting Company); Flying fish, Encyclopedia Britannica; Flying fish, Exocet, Barbados, et.al., Wikipedia; Coucou & Flying Fish, Barbados Pocket Guide; FLYING FISH GLIDE AS WELL AS BIRDS, Journal Of Experimental Biology; Facinating Flying Fish, physics central; Flying Fish Fly, Discovery.