An archerfish knocks insects off overhanging leaves with a jet of water, and to hit one it has to aim at a place where the insect doesn’t appear to be. Light bends as it crosses the surface, so from below everything above the water sits a little off, and the fish corrects for it, from steep angles and shallow ones. Researchers also report that it shapes the jet, so the back of the water travels faster than the front and catches up just short of the target, landing as one blob. Nobody taught it Snell’s law. Whatever it knows, it seems to know it the way most things are known before anyone writes them down: from the shots that missed.