Page 174 - Engineering in Nature

Engineering in Nature

The Incomparable Sensory System in Fish
Imagine that you are swimming along in a huge school of fish. If
every individual in it wants to suddenly turn right or left—and
what's more, in dim light or even darkness—will you be able to avoid
bumping into the other fish? Definitely not!

Yet such movements, impossible for us, are perfectly simple for
fish, because they have been created with a perfect sensory system
known as the lateral line. This system consists of dots or lines along
both sides of the body, containing sensory cells in a channel under the
skin. 54
The lateral lines immediately identify the slightest change in out-
side pressure, water movement, or strength or direction of the cur-
rent. In contrast to the sensory systems of land animals, fish use the
water's pressure waves and its feature of transportation and reserva-
tion of chemicals. Through these sensory systems, fish can half-feel
and half-hear vibrations. Thus they can determine the presence of a

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