Thursday 2 August 2012

In the dark


The streets of Gotham were pitch dark because of the power cut. It was almost midnight. Tom could barely see a few feet ahead. As he turned the corner, he became aware of someone behind him. The footsteps came closer and closer, and before he knew it, someone nabbed him by the throat, and threw him on the floor. The masked man pointed a knife at him and began searching him for his wallet. Tom lay helpless on the ground, too scared to react.

Suddenly, something swooped down and pushed the robber over. The figure in the dark started bashing the robber. Thankful, Tom got up to his feet. He wondered who his savior was. And then, he saw the savior’s outline in the dark. It was none other than batman himself!

Of course! Who else could have spotted danger in the dark!

Yes. Bats are nocturnal .i.e. they rest during the day and hunt at night. But how do they find their prey in the dark? The do it using a special ability called echolocation. As bats fly around in search of prey in the dark, they produce sounds by clicking their tongues or contracting their voice boxes. These sounds are very high-pitched, and cannot be heard by humans. These sound waves travel through air. When they hit a flying insect, they bounce off the insect, and start travelling back towards the bat. Using its ears, the bat detects these reflected waves and knows where the insect is.

The bat knows if the insect is on its left or right depending on which ear the waves reach first. It can also make out the size of the insect depending on the loudness of the echo. A smaller insect will reflect less waves, giving a softer echo. On the basis of the pitch of the echo, the bat knows in which direction the insect is moving. An insect that is moving towards the bat will give a higher pitched echo than the original sound, whereas an insect moving away from the bat will give a lower pitched echo. The bats mind unconsciously interprets this information, the way we humans unconsciously interpret the information from our eyes or ears as sight or sound.

The bat can also use this ability to locate stationery objects, and hence to find its way in the dark.



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