With roughly 28,000 species of fish in the world, there are many different hunting strategies. One of the most unique might be Toxotes, a genus better known as archer fish. These fish eat terrestrial insects, which might seem problematic. However, the fish are able to turn their mouths into souped-up squirt guns and blast their prey from several meters away. Peggy Gerullis and Stefan Schuster of University of Bayreuth performed a study to find out how these fish can be such accurate hunters by regulating the jets of water. The paper was published in the journal Current Biology.
These fish haven’t evolved a specialized organ used for shooting water; they’ve learned to work with what they have. Previous research found that by positioning the tongue along the roof of the mouth, the fish are able to create a structure like a gun barrel. Closing and squeezing the gills forces the water to shoot out and blast the intended target. This is especially impressive considering the fish need to account for the bending of light on the surface of the water. Though scientists now understand the mechanism behind this hunting technique and noted it could be regulated, the extent of the fish’s control had yet to be described.
Gerullis and Schuster trained nine archer fish (T. jaculatrix) to shoot at targets that were set up 20, 40, and 60 centimeters away. The process was recorded with a high-speed camera, in order to tease apart any nuances that might exist between the fish shooting at a nearer target versus one farther away.
One of the coolest aspects of this attack is that the water doesn’t hit the insect in a steady stream. Instead, the jet of water moves faster toward the back than it is at the front. It consolidates just before it gets to the prey, delivering a powerful wallop. The fish must take the distance of the prey into account when shooting, otherwise the stream won’t coalesce when it needs to, and the attack will be ineffective.
Archer fish open their mouths more slowly and use more water when shooting at targets that are farther away than when aiming at closer targets. This allows them to regulate the stream and make for a more successful attack.
The researchers state that the ability for archer fish to spit water to nab a tasty insect is fairly on par to our ability to throw and could be considered a form of tool use. As this trait is said to have contributed to our cognitive advances, it could indicate that archer fish are fairly brainy as well. There isn’t any evidence to suggest that archer fish are exceptionally intelligent yet, but that could be the focus of future study.
Science reports that Schuster will help develop a nozzle that builds off the principles of archer fish spitting. It could be used for water cutters or biomedical inkjet printing of tissues.