On electric fish, molecules and behaviour

By Fabiana Kubke 01/10/2009

If you are an electric fish swimming through the murky waters of South America or Africa, vision will not be of much use to navigate. To circumvent this problem electric fish evolved an ‘electric’ sense which they use for navigation and communication. These fish produce electrical discharges through specialized cells in their electric organs. Because the electric field the fish generates becomes distorted by objects within the field, the fish can use these distortions to ‘see’ their environment. 

A group from Harold Zakon’s lab at the University of Texas has now shown that electric fish can change the amplitude of their discharge during different levels of activity by literally changing the amount of ion channels that are put into the membranes of cells in the electric organ during day/night cycles. When the fish are more active, they load the cells with sodium channels, which makes the amplitude of the discharge larger, allowing them to detect signals at longer distances.

The concept that proteins can be trafficked in the cell around circadian rhythms, and social cues is pretty cool. You can read the original work by Markham, McAnelly, Stoddard and Zakon that was published in PLoS Biology 7(9): e1000203 thanks to the magic of Open Access. (Or you can read the briefer commentary by Fortune and Chacron here).

If you are wondering what the electric discharge of these fish looks like, you can watch this amazing video from the Hopkins Lab at Cornell University. They connected electrodes to the fish tank to capture the electrical signal that can be viewed in the oscilloscope, or heard through a speaker. Ok, granted, not as pleasant as a canary, but if you have a spare oscilloscope at home they make really cool (albeit geeky) pets.