Archer fish are the sharpshooters of the animal world, capable of hitting prey from metres away with pinpoint accuracy. The fish, Toxotes jaculatrix, which live in mangroves in southern and southeast Asia, achieve this by compressing their gill covers, and forcing water through a 'gun barrel' made by their tongue and the roof of their mouth.
To determine how the fish aim these water cannons, animal physiologists Peggy Gerullis and Stefan Schuster, who are both at the University of Bayreuth in Germany, trained the fish to fire at specific targets. They then used a high-speed camera to film the animals as they shot at targets of different heights. The researchers found that the fish adjusted the speed of the jets so that they were most focused and forceful just before reaching a target.
To do this, the archer fish controlled their water jets by adjusting the rate at which they opened and closed their mouths. When they needed to hit a faraway target 60 centimetres above the water, the fish sprayed water for a longer period of time, opening their mouth more gradually, than when aiming for a target 20 cm above the water. Gerullis and Schuster report their results in Current Biology1.
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