For scientists, it is a deep conundrum. For south-east Asian flies, it is an even deeper annoyance. How has the archer fish evolved to produce a jet of water more powerful than appears theoretically possible?
Now a group of Italian scientists believe they have found the answer: it is all to do with hydrodynamic instability.
Lurking under the surface in the brackish estuaries of India and the Philippines, the archer fish is the natural world’s great sniper. Watching the branches above the waterline, it waits for an insect to get within range then sprays a high-velocity stream of water. The