How do Bats Echolocate ?.Bats are not unique in their ability to use sound rather than sight to guide their flight and to hunt in darkness, but it is in these animals that the system has reached its apex of evolution.
In the late eighteenth century, the Italian naturalist and priest Lazzaro Spallanzani used blinded bats to prove that they could fly in complete darkness without colliding with objects in their path; he also showed that they lost this ability if their heads were covered. This hinted at the involvement of another sense. Charles Jurine, a Swiss zoologist and contemporary of Spallanzani, provided the first indication that sound was the key by blocking one ear of a bat. which then lost the ability to avoid obstructions in the dark. Jurine also demonstrated that the cochlea in a bat’s ear responds to sound frequencies beyond human perception.
The belief that bats use sound to map their surroundings was finally confirmed in 1940 bv Donald Griffin and Robert Galambos. Their work showed that bats produce ultrasound, which we cannot hear, and that they locate objects and judge distance by using its echo. They also demonstrated that bats employ echolocation for hunting moths in darkness, but later research adds a further twist to the tale: some moths have evolved the ability to detect bat ultrasound and can take avoiding action, while others emit high-frequency sounds, confusing the bat’s echolocation system — classic examples of an evolutionary ‘arms race’ between predator and prey.
Echolocation is not universal in bats: with a few exceptions only those of the insect-eating order Microchiroptera have a well-developed system. Echolocation has also evolved independently in unrelated birds and mammals, including oil birds and swiftlets that live in caves, some nocturnal shrews and toothed whales and porpoises, all of which operate in a sensory landscape beyond human experience.
