Archerfish

In some tropical swamps, there are silent hunters beneath the surface that shoot down their prey—with jets of water. If this fails, they simply jump out and grab their meal.

The remarkable hunting skill described opposite belongs to the unusual and beautiful archerfish. Normally, these fish feed on insects and other small creatures that accidentally fall into the water, like so many other fish species do. Some archerfish also feed on mangrove plants. However, their eyes are always turned skyward, keeping an eye out for any insect that may land on a twig or leaf near the water surface. When an archerfish spots a potential victim, it silently swims up to the surface and positions itself within

shooting distance. It then fires powerful jets of water at the prey through its specially adapted mouth. It can do this with such force that it can knock an insect off its perch from a distance of 5 feet.

The archerfish can shoot from under the water surface and hit a target perched in the open air because it can make an adjustment for the way light rays bend as they pass from water to air, and vice versa. If an archerfish were to aim its jets of water directly at where it sees an insect, it would always miss its prey. But it does not do this. The archerfish may not always be on target but, by making allowances for the different light-bending properties of air and water, it scores a hit often enough for the effort to be worthwhile. The skill has evolved to become an important part of the food-capturing armory of the archerfish.