Youtor
Archerfish target their prey with jets of water
>> YOUR LINK HERE: ___ http://youtube.com/watch?v=cpdfkj6Cxz8
Fish spits water like we throw spears. • Archerfish boast an unusual talent: They hunt by spitting powerful streams of water out of their mouths at unsuspecting above-water insects. Now, a new study reveals that this ability is even more remarkable than researchers thought: Like a true sharpshooter, the fish can use their mouths to adjust the focus of their water jets and maximize harm on prey at different distances. The finding hints that archerfish are smarter than previously thought, and it may inspire new technologies for inkjet printing and even cutting objects with water. • Fish spits water like we throw spears • http://news.sciencemag.org/biology/20... • Archerfish target shoot with 'skillfully thrown' water • http://www.eurekalert.org/pub_release... • Reference • Archerfish Actively Control the Hydrodynamics of Their Jets • Current Biology 2014 DOI: 10.1016/j.cub.2014.07.059 • http://www.cell.com/current-biology/a... • Highlights • •Archerfish shape the hydrodynamics of their jets to adjust them to target distance • •Shaping involves adjustments in the dynamics of mouth opening and closing • •As in human throwing, an extended striking range requires timing control • Summary • Among tool-using animals, none are known to adaptively change the hydrodynamic properties of a free jet of water—a task considered difficult in human technology. Hunting archerfish can strike their targets with precisely aimed water jets, but they are also presently thought to be unable to actively control the hydrodynamics of their jets. By using specifically trained fish, we were able to monitor several aspects of jet production and propagation as the fish fired at targets over a much wider range of distances than previously explored. We show that jets that have to travel farther also live longer. Furthermore, the time needed until water assembles at the jet tip is not fixed. Rather, it is adjusted so that maximum focusing occurs just before impact. Surprisingly, the fish achieve this by modulating the dynamics of changes in the cross-section of their mouth opening, a mechanism that seems to not have been applied yet in human-built nozzles. The timing adjustments archerfish make in order to powerfully hit targets over an extended range strikingly parallel the situation in the “uniquely human” ability of powerful throwing. Based on the key role throwing played in human encephalization and cognitive evolution, skillfully “throwing” water should similarly have led to the correlated rapid evolution of cognitive skills in this animal.
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