3. The Archerfish
The archerfish (genus Toxotes) has evolved to hunt land-dwelling insects perched on leaves and twigs up to two meters above the water’s surface by transforming its own mouth into a high-powered, biological water cannon. By pressing its tongue against a specialized grooved ridge on the roof of its mouth, the fish forms a narrow gun barrel. It then snaps its gill covers shut to force a high-velocity stream of water toward its target. Crucially, the fish actively alters the speed of the water jet during ejection—firing the tail end of the stream faster than the front. This causes the liquid to gather into a single, heavy impact droplet right before hitting the prey, delivering maximum kinetic force to knock the insect into the water. Even more impressively, the archerfish instinctively calculates Snell’s Law of Refraction to account for the severe bending of light at the water’s surface, adjusting its firing angle perfectly to ensure pinpoint accuracy on a target that isn’t actually where it appears to be.
