Fish spitting ability could improve human-designed nozzles

BBC : Archerfish strike their prey by shooting precisely aimed jets of water from their mouths. But rather than adjust the water pressure to achieve the distance and accuracy needed, the fish continuously change their mouth-opening diameter. To better study the phenomenon, Stefan Schuster and Peggy Gerullis of the University of Bayreuth in Germany trained two fish to hit small spheres at various distances. They found that as the jet of water sails toward the target, the water that travels in the jet’s stream catches up with the jet’s tip just before it hits the target—no matter the distance. That blob of water is essential for providing the force needed to dislodge the fish’s prey. The insight gained could prove useful in various human industries in which nozzles are used to shoot jets of fluid to cut or shape materials.