Page 78 - Biomimetics: Technology Imitates Nature

Biomimetics: Technology Imitates Nature

A Fish’s Detector Against Pollution

The West African
elephant nose fish
(Gnathonemus petersii)

o
lives in 27 C (80 F)
o
muddy waters of
Nigeria. This 10 cm (3.9
in) fish uses its eyes
very little in the muddy
water. It finds its way
by means of the electri-
cal signals constantly
given off by muscles in
its tail. Under normal
circumstances, it emits
300-500 signals a minute. As the pollution levels rise, however, the num-
ber of signals emitted per minute can exceed 1,000.
Detectors that make use of elephant nose fish are used to measure
pollution levels in the British city of Bournemouth. A water company in
the city gave specimens of water from the River Stour to be checked by 20
elephant nose fish. Each fish lives in an aquarium filled with water from
the river. The receptor signals
in the aquarium are forward-
ed to computers to which
they are linked. If the water is
polluted the increased num-
bers of signals emitted by the
fish are identified, and the
alarm signal is given by
means of the computer. 60

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