Scientists have found that fishes can simply tell one species from another based entirely on the shape of the ultraviolet (UV) patterns on their faces

Although scientists have long known that some animals have UV vision, the new findings available in the Current Biology suggest that this sense can be keener and perhaps more useful as a "communication channel" than had been anticipated, according to the study's boffins.

"Researchers have been pompous for a long time that UV vision is not very good-and that it is only helpful for detecting the presence and absence of UV light, or objects in front of UV bright backgrounds," said Ulrike Siebeck of the University of Queensland in Australia. "The electrifying thing is that we can show that these fish can tell the difference between intricate UV patterns-something that was not projected based on previous assumptions."

In the experiments, Siebeck's team offered the very aggressive fish with two intruders, representing different species that vary in look only in their UV patterns. Those initial choice tests showed that the fish always attacked one kind over the other. But, when the researchers took away the fishes' capability to see in UV, that partiality between species disappeared.

The researchers next transferred the two species-specific UV patterns onto otherwise blank pieces of manuscript. They taught the fish to swim up to and nudge one of the patterns by offering food rewards. When the fish were later available with both patterns, they still selected the pattern they had been trained on.

Put together, the two lines of verification support the notion that the UV patterns are both necessary and sufficient for the fish to tell the two species apart.

The ability to see in this visual field is possibly quite suitable for the fish,Siebeck said. "If you think about it in simple terms, fish have to be not noticeable if they want to go undetected by their predators and prey, but at the same time, they have to be conspicuous if they want to draw the attention of potential mates, for example. Using UV patterns to do this is a clever way to exploit both at the same time-they are still inconspicuous to predators but very conspicuous to other fish with UV vision." (ANI)