How do bats see with sound? Echolocation explained

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1 / 10 A cave with no lightThere is no light in this cave. The bat has sent one call; the bright shell is the sound spreading out at 343 m/s. Tap Click to call again, or follow these steps.

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01
A cave with no light
There is no light in this cave. The bat has sent one call; the bright shell is the sound spreading out at 343 m/s. Tap Click to call again, or follow these steps.
02
The call spreads as a beam
Seen from the side, the shell is bright in front of the bat and fades toward the sides. The faint cone shows the beam. Sound in air is fast, so the picture is slowed down 100 times.
03
Echoes come back from the columns
Where the shell touches rock, a weak echo starts back. When it reaches the bat a point appears. A column 10 m ahead answers after 58 ms: the sound went 20 m, out and back.
04
Calls build a map
The bat calls about ten times a second while searching and turns its head a little each time. Points from many calls build up into the shape of the tunnel. Older points fade.
05
An echo from a moth
The moth’s echo is the orange spot. It is far weaker than the wall’s, so the bat hears it only within a few metres. The readout shows the echo delay and the frequency of the returning echo.
06
Approach and terminal buzz
Closing in, the bat shortens its calls and calls faster: about 40 a second on approach, then more than 160 a second in the final buzz. Each echo is home before the next call leaves.
07
Horseshoe bats listen for the Doppler shift
This bat sends one long tone near 82 kHz through its nose. Flying forward raises the echo’s pitch, so it lowers its call until the echo comes back at the pitch its ears hear best.
08
Smooth water is a hole in the map
The pool is a mirror for sound: calls bounce off and away, so its area stays dark. In experiments bats tried to drink from smooth plates for the same reason.
09
A tiger moth jams the sonar
Some tiger moths answer an attack with bursts of ultrasonic clicks. The moth’s echo smears into red points at the wrong distance, and in this model the hunt usually fails. Tap Hunt the moth to try.
10
What a lamp would show
With the lamp on you see the cave as your eyes would. The echo map shows the same walls, columns and drips. Turn the lamp off and that map is all the bat has.

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