According to a duo of German ichthyologists reporting in the Current Biology, archerfish are much more adaptable and skillful target-shooters than previously thought.
Banded archerfish (Toxotes jaculatrix) jetting water at an insect. Image credit: Ingo Rischawy / Schuster lab / University of Bayreuth.
Archerfish are a small family (Toxotidae) of fish comprising one genus and seven species.
They can be found in brackish waters of estuaries and mangroves from India to the Philippines, Australia, and Polynesia.
These fish exhibit the remarkable ability to hunt for insects and other small terrestrial animals by firing precisely aimed jets of water that knock prey onto the surface of the water. They can bring down their prey up to 3 m above the water’s surface.
Now, ichthyologists Dr Peggy Gerullis and Dr Stefan Schuster of the University of Bayreuth in Germany have found that archerfish can actively control the hydrodynamics of their jets.
By using specifically trained banded archerfish (Toxotes jaculatrix), the scientists were able to monitor several aspects of jet production and propagation as the fish did their thing.
The experiments showed that the time needed before water masses up at the jet tip isn’t fixed. Rather, archerfish make adjustments to ensure that a nice drop of water forms just before impact.
Surprisingly, the fish achieve this by modulating the dynamics of changes in the cross-section of their mouth opening.
“The timing adjustments that archerfish must make to powerfully hit their targets over an extended range are surprisingly comparable to the ‘uniquely human’ ability of powerful throwing,” the scientists explained.
“It’s possible that the mechanism the fish use to control water with such precision might also find application in human-built nozzles.”
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Peggy Gerullis & Stefan Schuster. Archerfish Actively Control the Hydrodynamics of Their Jets. Current Biology, published online September 04, 2014; doi: 10.1016/j.cub.2014.07.059
