If you look carefully at the snout of a dolphin, you’ll see two rows of tiny pits, known as vibrissal crypts, When dolphins are born, these pits house whiskers that soon waste away to leave empty craters. It’s tempting to think that the crypts as useless evolutionary throwbacks to a time when the ancestors of dolphins used whiskers to feel their way about. But these structures are far from useless. In at least one species of dolphin, they can sense electricity.

Nicole Czech-Damal from the University of Hamburg discovered this amazing ability by studying the Guiana dolphin, also known as the costero. It looks a lot like the familiar bottlenose dolphin, but its vibrissal crypts are far larger. Back in