How Does a Bat Use an Echo?

Mechanism

• After emitting sonic pulses, bats hear the echoes through their ears, which subsequently direct the sound through the inner ear and onto the basilar membrane of the cochlea. According to the University of Illinois, the basilar membrane is highly specialized to the task of echolocation and its thickness is related to the precise frequencies the bat is interested in receiving. After being transmitted into neural code, the bats' specially evolved brains create amazingly accurate pictures of objects close to them.

Uses

• The main use of echolocation is for hunting at high speeds in total darkness. Echolocation also allows bats to exploit habitats that other creatures find unsuitable. For example, they can navigate through the darkened tunnels and around the sudden protrusions that are features of cave habitats. Bat Conservation International reports that bats can also differentiate the ultrasonic echolocation calls that other bats make. This may explain how bats can remain in large groups while flying.

Types

• Bats able to echolocate are of the suborder Microchiroptera, which contains approximately 800 species of bats. The sounds produced by the different species for echolocation vary widely and range from clicks to bisonar pulses. At upwards of 30kHz, the sounds produced by bats are beyond the range of human hearing. As well as the different sound of their calls, bats vary in the frequency of these sounds. For example, the mustached bat produces signals 80 percent of the time that it spends echolocating.

Developments

• Many scientists have dedicated their careers to researching the use of echoes by bats. Nevertheless, according to Scientific American, scientists remain unsure about "many of the precise biological and evolutionary mechanisms that make this skill possible." One clue was found by scientists from the University of Western Ontario in Canada, who discovered that species of bats that use echolocation had a unique skeletal feature -- a bone called the "stylohyal" that physically connects the larynx to the ear bone. They suggest this might be used to dampen sound vibrations and prevent the bat from deafening itself.