Page 86 - Engineering in Nature

Engineering in Nature

These are estimates regarding the possibilities the moth uses in de-
ciding about the bat and the sort of system employed. There is also
the behavior of the moth that can be clearly observed.
When identifying and attacking prey, bats emit increasingly dense

sound waves. If the moth perceives a weak sound coming from oppo-
site side, the moth immediately changes course, returns and moves
away, leaving the bat behind it. That's because the weakness of the
sound means that the bat has not yet located the moth and therefore,
has not yet begun pursuit. That is because bats emit increasingly
dense sound waves when identifying and attacking prey. A moth
which detects weak waves changes direction and moves away, leav-
ing the bat behind it. If the moth detects dense signals, it either makes
a sudden dive towards the ground, or makes a series of acrobatic ma-
neuvers of sharp turns to escape the bat.

• The Moth's Support Systems
The moth's two ears let it locate the direction of the sounds it hears.
If the bat is to the moth's left, sound waves coming from the that di-
th
rection are detected about 1/1000 of a second before to those coming
from the right. This perception gap between the two ears is enough
for the moth to locate the source of the sound.
Nor is this the end of the moth's ear's astonishing features. Some
moths' ears are covered with a membrane-like structure that serves in
much the same way as our external ear. By collecting sound, it con-
tributes to the strengthening of hearing capacity.
In addition, some moths do more than just detect ultrasonic
sounds, but can also emit them. When these moths detect a bat, in-
stead of fleeing, they emit ultrasonic sounds of their own. One might

imagine that to do such a thing would mean committing suicide for a

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