“Mormyrid electric fish rely on the waveform of their electric organ discharges (EODs) for communicating species, sex, and social status, while they use the sequences of pulse intervals (SPIs) for communicating rapidly changing behavioral states and motivation.” (Wong and Hopkins 2007:2244)
“Two other fish, the mormyrids and the knifefish gymnotids, use their
electric organs to navigate. These organs create an electric force
field that surrounds the fish as it swims, and is modified by the
relative conductivity of objects in the fish’s immediate surroundings.
The fish detects and interprets these electrical fluctuations through
electroreceptors embedded in its body, so that it has a constantly
changing electrical image that enables it not only to navigate
effectively around obstacles in even the darkest water but also to
sense nearby prey, and anything else coming its way.
mormyrid’s detection mechanism is so sensitive that it can distinguish
between different species of fishes, and also between different sexes
of its own species. In 1992, studies were conducted by Dr. Christian
Graff from Pierre Mendès-France University in Grenoble, France, and Dr.
Bernd Kramer of Germany’s Regensburg University, using mormyrids
specially trained to respond to certain signals. The studies revealed
that these fish could even distinguish between different same-sex
individuals of their own species. They detected and recognized the
unique characteristics of pulse and frequency emitted by each
individual.” (Shuker 2001:53-54)