Courtney Ladbrook, of Balclutha School, asks :-

How do flying fish fly?

Mark Lokman, an aquaculturist and fish biologist at the University of Otago, responded.

Flying fish live in warm waters and belong to the group Exocoetidae - probably from the Greek word exocoetus (note the similarity with exocet, the French word for flying fish), meaning a fish that sleeps on the shore.

The gracious glides of flying fishes and their occasional landings on the deck of a boat can cause a stir. Their 'wings' are enlarged fins. Exocoetid flying fish come in two types - the 'two-wing' type, in which only the pectoral ('front') fins are enlarged, and the 'four-wing' type, in which both the pectoral and pelvic ('rear') fins are enlarged. The enlarged pelvic fins of four-wingers mostly function to stabilise flight, and it has been suggested that the four-wingers may cover larger distances.

Films of flying fish show that they glide. No flapping of the fins occurs during flight. As a generalisation, flying fish fly by completely leaping out of the water under shallow angles (around 30 degrees) at high speed (20 to 30 body lengths per second) with their pectoral fins rolled up against their bodies. Once in the air, they spread their fins. This does not provide the momentum for the flight. Such momentum comes from 'taxiing' ie making a series of very rapid strokes (some 30 complete strokes in less than 1 second) of the rigid, asymmetrical tail, which has the bottom lobe larger than the top lobe. This is followed by flight, or rather, gliding, for around five seconds at speeds up to 70 km/h and maximum height of as much as eight meters depending on wind speed and direction. Towards the end of flight, the flying speed drops and so gravity draws the fish back to the sea surface. There, the fish can elect to submerge, or to repeat the taxiing and carry on for additional gliding stints.