Bats are mammals which use sound ways to locate their prey. They do so by a scientific technique called 'Echolocation'. This is because they are nocturnal mammals that have weak eyesight. They use their ears more than any other mammal.
It is defined as the use of sound waves and echoes to determine the location of objects in space. Bats use this mechanism for finding their food. Just as SONAR (Sound Navigation and Ranging) is used in case of big ships, and tanks, similarly, the emission of sound waves helps bat catch its prey.
Bats use ultrasonic waves (20 to 200 kilohertz) to catch their prey.
Most bats produce a complicated sequence of calls, combining Constant Frequencies and Modulating frequency components. Their sounds are reflected in the environment, hitting various objects and returning to the bat as echoes.
The echo signals enable the bat to judge the whereabouts of the surroundings and form some sort of mental image of it. Now, in order to reach its prey (about which a mental image has already been formed), bats continuously hurl and glide in curved flight trajectories, using large movements to propel themselves.
Not only a vague judgment exists, but Bats have some navigational ability to measure how fast the flight angle is changing as they approach their targeted prey also.
SONAR is used in case of submarines, echolocation, on the other hand, is used by bats to catch its prey. SONAR is used in water bodies, while Bat uses echolocation in the open air.
Thus, these nocturnal creatures are bestowed with inherent qualities by nature which help them catch their prey with nearly accurate exact measurements even if they have weak eyesight.