Researchers from the University of Trento have found that archerfish can understand the difference between numbers via experimentation. Davide Potrich, Mirko Zanon and Giorgio Vallortigara are the name of the three researchers and they have published their research paper on the bioRxiv preprint server. They have described in the paper the experiments they have conducted with the spitting fish.
Archerfish capture their prey by placing their mouths at the surface of the water. Then they send a stream of water into the air at a target. The targets are then overcome by the jet and fall into the water below. This allows the fish to hold and swallow the prey.
Previous research has proved that archerfish also suffer from social awkwardness. These fishes hesitate while shooting prey when others of their species are watching them. In their new research, the researchers have used the spitting techniques of Archerfish to test number differentiation in fish.
The researchers have situated the fishes in a tank of water and then placed a pair of disks over the top of it. They have marked the disks with different numbers of dots. The researchers taught the fish to spit at disks. The disks had certain number of dots on them.
Then they showed the fish a row of disk pairs with various numbers of dots on them. The scientists found out the fish was spitting on the disk which has the certain numbers of dots that they had been thought to spit in. They also changed the number of dots the fish had to choose from. But they found that the fish were still able to identify the right disk.
They have also tested the fish with different size of dots. They found out that the fish is still spatting at only the disk they had been trained to recognize. The scientists then changed the disks that did not have the number of dots the fish had been taught to recognize. Then also they found that the fish chose the lower number of dots and the number they had been trained to recognize was lower than the alternative.
Scientists think that the fish is able to identify the dots in order to figure out which they are supposed to target.