Echolocation is a form of biological sonar which is used by several kinds of animals by emitting calls and listening for the echoes of these calls in order to discern the distance between objects and themselves. These echoes are used for navigation and foraging or hunting in various environments. Animals which use echolocation are mostly mammals, though some birds are capable of using it as well; namely, toothed whales and dolphins, some shrews, bats, oilbirds, and cave swiftlets. The term “echolocation” was first coined by Donald Griffin in 1938, who conclusively demonstrated its existence in bats, though Lazzaro Spallanzani had concluded that bats used their hearing rather than vision to navigate in dark environments in the 18th century.
Bats, specifically, are the most famous animals capable of using echolocation and use it to navigate and hunt in total darkness. As bats are nocturnal, emerging from their roosts at dusk, it was naturally important for them to evolve some means of navigating the nighttime skies, and echolocation evolved as a result. Echolocation in bats is a form of ultrasound generated by the larynx and transmitted through the open mouth or (in horseshoe bats) the nose; these sounds are mostly beyond the range of human hearing.
