Page 68 - Biomimetics: Technology Imitates Nature

Biomimetics: Technology Imitates Nature

It has long been known that bats use their sonar system to find their
way around in the pitch dark. Recently, researchers have uncovered new
secrets of how they do it. According to their research, the brown insectiv-
orous bat, Eptesicus fuscus, can process two million overlapping echoes a
second. Furthermore, it can perceive these echoes with a resolution of on-
ly 0.3 millimeters (1/80 th of an inch). According to these figures, bat's
sonar is three times more sensitive than its man-made equivalent. 50
Bats' sonar navigational skills teach us a great deal about flying in
the dark. Research carried out with infrared thermal imaging cameras and
ultrasound detectors afforded considerable information about how bats
fly in search of prey at night.
Bats can seize an insect from mid-air as the insect rises from the
grass. Some bats even plunge into bushes to capture their prey. It’s no
easy task to seize an insect buzzing in the air using only reflected sound
waves. But if you consider that the insect is among the bushes, and sound
waves bounce back from all the leaves surrounding it, you will grasp
what an impressive task the bat actually performs.
In a situation like that, bats reduce their sonar squeals, to prevent
their becoming confused by echoes from the surrounding vegetation. Yet
by itself, this tactic isn’t enough to enable bats to perceive the objects in-
dividually, because they also need to distinguish the arrival time and di-
rection of the overlapping echoes. 51
Bats also use their sonar when flying over water to drink, and in
some cases, to capture prey from the ground. Their expert maneuverabil-
ity can best be seen when one bat chases another. Understanding how
they can do this will let us produce a wide range of technological prod-
ucts, especially equipment for sonar navigation and detection. Moreover,
bats’ broad-band sonar system is also imitated today in mine-sweeping
technology. 52

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