Question
Explain how bats use ultrasound to catch a prey.
Solution
i) Bats can produce and receive ultrasonic waves.
ii) During its flight, a bat emits ultrasonic waves. The bat receives back these waves after being reflected by the obstacle in its path.
iii) The bat gets information where the obstacle or prey is and what is its size, because of the nature of these waves. 
Fig. Ultrasound is emitted by a bat and it is reflected back by the prey.
Porpoises also use ultrasound for navigation and location of food even in total darkness.
