Animation by Wake Forest
STAR Ryan Hupp
Have you ever heard
someone use the phrase "blind as a bat"? Well the truth is bats
really aren't blind. The have perfectly good eyes and they also have a
special ability that allows them to "see" in the dark. Over
200 hundred years ago an Italian monk named Lazaro
Spallanzani did some experiments that showed that bats navigate
in the dark using their mouths and their ears. Bats send out short, high
cries and listen for the echoes. Try this sometime. Close your eyes and
clap you hands loudly. Do you hear any echoes? Bats do. They can detect
the echoes from the flying insects that they eat. Not only that. They
can tell the direction in which the insects are flying, their speed, their
size, their shape, and even their texture. What a talent!
If you use a bat
detector to listen to a bat feeding by echolocation you can figure
out a lot about what is going on. This is because echolocation has four
phases. When a bat is "searching" for food it produces cries
slowly (about 10 cries/second). When it detects an insect it begins its
"approach". During the approach in speeds up its cries (20 to
40 cries/second) to obtain more information about its prey. It then "tracks"
its prey very carefully being sure that the echoes do not get too loud
and then it begins its "terminal buzz". During its terminal
buzz the bat emits cries at a very rapid rate (100-200 cries/second).
The echoes give it all the information that it needs to catch the insect.
The bat usually does not catch the insect in its mouth. Instead it uses
the membranes between its tail and its hind legs like a baseball glove
and catches the insect. When successful it tucks its head down into its
glove and grabs the insect with its teeth.
If you would like to listen to the
echolocation cries of a bat click on the icon below. The bat cries have
been slowed down so that you can hear them. This sequence is slowed down
about 10 times.
MP3 format: Bat Echolocation
Sound Sounds recorded and provided by Nickolay Hristov
WAV format: Bat Echolocation
The video sequence shown below is slowed down ~25 times.
Click here to see a bat
catch a moth on infrared video!
Video sequence provided by Nickolay Hristov