Archerfish shoots prey with 'skillfully thrown' water

Asia's Archerfish is known for shooting land-based insects and other small animals with jets of water, but a new study out on Thursday found that they can actually fine-tune their jets for a precision strike, making them the first known animal to use adjustable jets of water as tools.

The study, published in the US journal Current Biology, showed that those fish, which can bring down insects and other prey more than two meters above the surface of the water, are much more adaptable and skillful target-shooters than anyone had previously thought and may be even comparable to true sharpshooters.

"One of the last strongholds of human uniqueness is our ability to powerfully throw stones or spears at distant targets," study author Stefan Schuster of the University of Bayreuth in Germany said in a statement. "This is really an impressive capability and requires -- among many fascinating aspects -- precise time control of movement. It is believed that this ability has forced our brains to become bigger, housing many more neurons to afford the precision. With the many neurons around, they could be used for other tasks apart from applying them for powerful throws. It is remarkable that the same line of reasoning could also be applied to archerfish."

The researchers made the discovery by first training the fish to hit targets ranging in height from 20 to 60 centimeters from a precise location. They then monitored various aspects of jet production and propagation as the fish did their thing.

The study showed that archerfish make adjustments to ensure that a nice drop of water, like a bullet, forms just before impact.

Surprisingly, the researchers reported that the fish achieve this by changing the cross-section of their mouth opening.

It's possible that the mechanism the fish use to control water with such precision might also find application in human-built nozzles, Schuster said, noting that adjustable jets are big business in many industries, including medicine.

"The biggest problem is how to modify the abrasive properties of a jet," Schuster said. "Usually this is done by modulating the release pressure or by varying the abrasives added to the jet. We are not aware of someone actually using a dynamically adjustable valve."