Commentary Type

Invited Commentary


The weakly electric knifefish Eigenmannia emits an electric organ discharge (EOD) of constant frequency and sinusoidal waveform that varies with sex and age. Eigenmannia discriminates among these except when stimulated at the same frequency as its own EOD frequency. In that case, it needs to perform a Jamming Avoidance Response (frequency shift) which results in a beating mixed signal. By a sophisticated analysis of the amplitude and phase modulations of the beat signal, Eigenmannia derives the frequency difference, its sign, and the waveform of the stimulus, hence the signaller’s identity. The human ear is not capable of an equivalent waveform analysis of acoustic stimuli.

Author Biography

Leo Bernd Kramer was professor at the Zoological Institute of the University of Regensburg (Germany) until he retired (2009). His research was on behavioural, sensory and ecological biology with a special interest in electrocommunication.