7 BIO - EOC - Biological Evolution; Unity and Diversity 1

Bats navigate in darkness by emitting high-pitched, ultrasonic sounds that humans cannot hear. They create maps of their environments based on how the sound waves bounce back. This is called echolocation.

Bats also use echolocation to find food at night, such as moths. In response, some moths have developed mechanisms to avoid being eaten by bats. These moths have specialized tympanal organs that vibrate when hit with high-frequency sound waves, acting like simple eardrums. Moths can also generate their own ultrasonic sounds to confuse the bats’ echolocation.

Figure 1 shows a bat and a moth using echolocation.

Moths vary in their behavior response to approaching bats. Some moths fly quickly away, and some display evasive flight patterns, like flying in loops and dives. Other moths release ultrasonic clicking noises that interfere with the bat’s echolocation. Figure 2 shows the effectiveness of these moth responses that help them avoid capture by bats.

Some bats have developed the ability to produce different echolocation frequencies to which moths cannot produce a counter-response. Certain species of bats also use echolocation to counter the sounds made by other bats.

The effectiveness of echolocation depends upon the distance at which bats and moths can hear each other at different volumes, as shown in Figure 3.

Scientists studied the history of the development of specialized organs in moths and bats. They determined that moths emerged 150 million years ago (mya) and bats emerged 65–90 mya, as shown in Figure 4.