A four-year study into the amazing water shooting abilities of the archerfish (Toxotes jaculatrix) has revealed why the aim of these fish is so accurate.
A team from the University of Bayreuth in Germany trained a group of nine of the fish to spit water at insect prey in a specific location in the aquarium, to allow it to be recorded using a high speed video camera and the force and velocity of the water measured.
The study found that archerfish continually change the shapes of their mouths as they spit the water, therefore altering the speed and stability of the outgoing stream to ensure it aims at and hits the target — essentially altering the properties of moving water.
In addition, the archerfish shoots water at the end of stream at a faster speed than at the beginning, so the back of the water jet catches up with the front end — and it all hits the target at once with maximum force.
Researchers say that this means the archerfish uses water as a tool, with the precision of its timing and movement comparable to a human throwing a spear.
The report is published in Current Biology.
Why not take out a subscription to Practical Fishkeeping magazine? See our latest subscription offer.
Don't forget that PFK is now available to download on the iPad/iPhone.