Page 80 - Design in Nature

BAT RADAR RADAR SONAR
(Eptesicus) (SCR-268) (AN/APS-10) QCS-T

Weight of system (kg) 0.012 12,000 90 450
Peak Power Output (W) 0.00001 75,000 10,000 600
Diametre of Target (m) 0.01 5 3 5
9 -5 -2 -3
Echolocation Efficiency Index 2x10 6x10 3x10 2x10
Relative Figure of Merit 1 3x10 -14 1,5x10 -11 10 -12

The system used by bats to locate their prey is millions of times more efficient and accurate
than manmade radar and sonar. The table above clearly illustrates these properties.
"Echolocation efficiency index" is range divided by the product weight times power times
target diametre. "Relative figure of merit" compares the echolocation efficiency indexes with
the bat as 1.

faces the potential problem of not being able to hear the echoes of its sounds
from a fly that moves away.

Nevertheless, this is never a problem for the bat because it adjusts the
frequency of sounds that it sends towards moving objects as if it knows
about the Doppler Effect. For instance, it sends the highest frequency sounds
to a fly moving away so that the reflections are not lost in the inaudible
section of the sound spectrum.

So, how does this adjustment take place?
In the brain of the bat, there are two kinds of neurons (nerve cells) that
control its sonar systems; one perceives the reflected ultrasound and the
other commands the muscles to produce echolocation calls. These two

neurons work in such complete synchrony that a minute deviation in the
reflected signals alerts the latter and provide the frequency of the call to be
in tune with the frequency of the echo. Hence, the pitch of the bat's
ultrasound changes in accordance with its surroundings for maximum
efficiency.
It is impossible to overlook the blow that this system deals to the

explanations of the theory of evolution through coincidence. The sonar
system of bats is extremely complex in nature and cannot be explained by
evolution through arbitrary mutations. The simultaneous existence of all
components of the system is vital for its functionality. The bat has not only
to release high pitch sounds but also to process reflected signals and to
manoeuvre and adjust its sonar squeals all at the same time. Naturally, all of