Several hundred species of fish have evolved the ability to generate electric fields, which they use to navigate, communicate and home in on prey. But this ability comes at a cost – the electric field is generated continuously throughout life, so consumes a great deal of energy, and it can also attract predators which are sensitive to it. Electrogenic fish species therefore utilize various strategies to save energy and to minimize the likelihood of being detected. Some generate irregular pulses of electrical discharges whose rate can be modulated; others can also modulate the strength of the electric field.
The cellular and molecular mechanisms underlying one of these behavioural adaptations are now revealed in a beautiful study published in the open access journal PLoS Biology. It shows that in one species of electric fish, circadian cues and social encounters regulate the movements of proteins called voltage-gated sodium channels – which are crucial for generating the electric field – in cells of the electric organ. At night, low light levels and social interactions drive the insertion of sodium channels into the cell membranes, leading to a dramatic increase in the strength of the electric field.