Bats , Whales and Dolphins have echo sensors. They used it to sense an object in the way. First they squeak than wait till it bounces back. if it doesn't come back than they know something is not on the way. if it does come back they know something is in the way. This is Echolocation.
Bats use their sensitive ears to hear small noises and big ones. To find its prey they sent signals called echo's. Bats normally eat Flies and insects. When they find their prey they stop and eat. This is about bats finding their prey