Fish
Flying Fish
Exocoetidae · also called flying fish, flyingfish
A flying fish does not flap, but it does leave the water — bursting out at a shallow angle, spreading fins that work exactly like wings, and gliding across the open ocean for the length of a football pitch to shake off a tuna.
Overview
Flying fish are a family of about 65 species living at the surface of warm oceans worldwide. They feed mostly on plankton and small crustaceans strained near the surface at night. Most are 15–30 cm long, with a torpedo body, hugely enlarged pectoral fins, and a tail whose lower lobe is much longer than the upper.
The glide
Chased, a flying fish accelerates to about 60 km/h underwater, angles up through the surface, and spreads its stiff fins to glide — typically 30–50 m per glide, a metre or so above the water. When it sinks back down it can keep the long lower tail lobe beating the surface at up to ~70 beats per second, a built-in outboard motor that relaunches it. Chaining glides, it can cover 400 m in one escape.
Two wings or four
Some species also enlarge the pelvic fins, becoming “four-winged” gliders with extra lift; others rely on the pectorals alone.
Why glide
It is an escape from underwater predators — tuna, marlin, mahi-mahi, squid — that cannot follow a fish out of the water. The catch is that frigatebirds and other seabirds snatch gliding flying fish from the air.
Status
Flying fish are Least Concern and abundant, an important prey base for open-ocean predators, and the basis of sustainable fisheries — the crunchy orange tobiko on sushi is flying-fish roe.
Flying Fish: common questions
Do flying fish actually fly?
They glide rather than fly — there is no flapping of the "wings" to generate thrust, which is what defines true powered flight. A flying fish gets all its energy underwater — it swims hard, up to about 60 km/h, aims for the surface, and shoots out at a shallow angle. Once airborne it holds its enlarged pectoral fins stiffly outstretched like an aircraft's wings, and air moving over them provides lift while gravity and drag gradually bring it back down. The one active trick happens at the end of a glide — the fish can drop its tail so the long lower lobe dips into the water and beats rapidly, acting like an outboard motor to push the fish back up to gliding speed without a full landing. By repeating this it can string glides together.
How far and how high can a flying fish glide?
A single glide typically covers 30 to 50 metres and lasts a few seconds, at a height of around half a metre to a metre and a half above the surface — occasionally higher if an updraft off a wave lifts them. By taxiing and relaunching several times in succession, a flying fish can stay "in flight" for 30 seconds or more and cover a total distance of up to about 400 metres in one escape sequence. Sailors have long reported flying fish clearing the deck rails of ships, which for a low freeboard vessel means heights of several metres, usually achieved with the help of wind and wave lift.
Why do flying fish glide?
Almost certainly to escape underwater predators. Flying fish are a staple food for fast open-ocean hunters — tuna, marlin, dolphinfish (mahi-mahi), and squid — and once one of those is chasing you through open water with no reef or weed to hide in, leaving the water entirely is a very effective evasion. The predator loses sight of the fish, cannot follow, and by the time the flying fish re-enters it may be 50 metres away and travelling in a new direction. The cost is that gliding flying fish are then exposed to frigatebirds and other seabirds, which snatch them out of the air, so it is a trade-off rather than a perfect defence.
Are flying fish caught and eaten by people?
Yes, extensively in some places. Flying fish are a cultural and culinary icon of Barbados, which is sometimes called "the land of the flying fish" and where they are the national dish served with cou-cou; the fishery uses anchored rafts or screels that the fish gather under, plus nets and lines. Flying fish and especially their roe (tobiko) are also important in East and Southeast Asian cuisine — the bright orange, crunchy roe on sushi is flying-fish eggs. The fisheries are generally considered sustainable because the fish are short-lived, mature quickly, and breed prolifically, though catches around Barbados have shifted with changing ocean conditions.