Echolocation is a biological sonar used by several animal groups, both in the air and underwater. It is a technique used by some animals, such as bats, dolphins, and whales, to determine the location of different objects in the world around them using sound waves. Animals that use echolocation emit sound waves that bounce off objects around them. From the returning echo, the animal can tell the distance, size, and even the texture of the objects around them. Echolocation is used for navigation, foraging, and hunting prey.

Many animals use echolocation, including most bats, all toothed whales, and small mammals. Some birds, such as the oilbird and certain cave swiftlets, also use echolocation. Animals have several methods for echolocation, from vibrating their throats to flapping their wings.

Echolocation allows animals to move around in pitch darkness, so they can navigate, hunt, identify friends and enemies, and avoid obstacles. For dolphins and toothed whales, this technique enables them to see in muddy waters or dark ocean depths, and may even have evolved so that they can chase squid and other deep-diving species. Echolocation allows bats to fly at night as well as in dark caves, which is a skill they probably developed so they could locate night-flying insects that birds can’t find.

Humans who are blind or vision-impaired can also use echolocation to navigate their environment. They make clicks, either with their tongues or an object, like a cane, and then navigate via the resulting echo. Brain scans of echolocating humans show the part of the brain that processes vision is employed during this process.