Archerfish: The snipers of sea

WASHINGTON, Sept. 4 (UPI) -- Most fish wait for their land-based prey, whether insects or small rodents, to fall into the water -- whether on purpose or on accident -- to get their eat on. It's much easier that way. But archerfish aren't that patient, and they don't have to be, because they have a specialized mouth that allows them to shoot droplets of water at insects hovering above the water -- like a little living squirt gun with scales.

Archerfish prefer brackish waters and are often found among the mangroves of India, Philippines, Australia and Polynesia. Researchers suggest they're the first tool-using animal to "adaptively change the hydrodynamic properties of a free jet of water." It's this remarkable ability that allows them to take down flying insects, dangling spiders, and even small lizards from tree limbs overhanging their habitat.

Recently, researchers from the University of Bayreuth, in Germany, spent several months observing the fish's hunting techniques. Their findings are detailed in the latest issue of the journal Current Biology. Scientists were surprised to find that archerfish are exceptionally accurate and adaptive in their water-shooting abilities.

"The predominant impression from our field work in Thailand over several years is that there is very little to actually shoot at, so it's important for the fish to be efficient," study author Stefan Schuster explained in a recent press release. "It pays to be able to powerfully hit prey over a wide range of distances."

To do this, the fish are able to adjust their mouth on the fly -- augmenting how the water forms in its mouth and the way it's ejected. These adjustment ensure that a sizable drop of water forms just before impact with the fish's target. Researchers have likened the technique to the sorts of adjustments humans instinctively make when slinging an object at another object at long distances.

"One of the last strongholds of human uniqueness is our ability to powerfully throw stones or spears at distant targets," Schuster said. "This is really an impressive capability and requires -- among many fascinating aspects -- precise time control of movement."

Schuster and his colleagues this complex method of hunting forced human brains to become bigger and ultimately aided our transformation into intelligent beings. He says this same mechanism is present in archerfish.