Page 84 - Design in Nature

82 DESIGN IN NATURE

Gnathonemus Petersi

The ampullary receptors cannot perceive the high frequency signals
transmitted by the fish. This is accomplished by a tubular receptors. These

sensors are sensitive to fish's own discharge and they work to map the
surroundings.
By means of this system these fish can communicate and warn one
another against any threats. They also exchange information about species,

age, size and gender.

Signals Describing Gender Differences
Each species of electric fish has a unique signature signal. Furthermore,
there can be differences among the individuals of a species. However, the
general structure remains unchanged. Some details are particular to the

individual. When a female runs across a male fish it immediately senses it
and behaves accordingly.

Signals Describing Age
Electrical signals also carry information on the age of these fish. A

newly hatched fish bears a different signature from an adult. The signals of
the newly hatched fish maintain their characteristic until the fourteenth day