Page 59 - Engineering in Nature

ll living things must know what is going on
around them, or else they'll be unable to find
food, protect themselves from danger, and find
mates. Therefore, every living thing needs sys-

tems to let it distinguish objects and exhibit the
necessary reactions in order to survive.
These special systems that tell them about external objects and di-
rect their actions vary among species. The auditory receptors of a spe-
cies of moth that needs protection from bats are sensitive to the
high-frequency cries emitted by bats. Bats, in turn, hear the echoes of
the sounds they emit at various frequencies, and manage to fly and
hunt in the dark without hitting anything by analyzing those data.
Similarly, salmon's olfactory systems allow them to swim for thou-
sands of kilometers (hundred of miles) back to the streams where
they were spawned. Whales communicate by perceiving the sounds
they emit.
Direction finding systems, infra-red eyes and special hearing sys-
tems are just a few of the perception systems that living things em-
ploy. As will be seen from upcoming examples, one common feature
of these systems is that all the components that permit perception are
fully integrated with the other organs essential to survival. For in-
stance, smell receptors in the nose are compatible with the smell cen-

ter in the brain. The perceptions resulting from this harmony may
have different meanings for each species, such that a living thing can
distinguish members of its own species solely from their scent. Again,
the receptors in a living thing's light-sensitive regions are entirely

Adnan Oktar
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