You’ve probably heard of electric eels but did you know that there are electric bacteria? Or that humans also use electricity physiologically?
Information is sent around our bodies via electric signals, little pulses of voltage called action potentials. These potentials are created by changing the concentrations of ions across cell membranes. Before a signal arrives at a cell, it is filled with potassium ions (negatively charged), with sodium ions (positively charged) on the outside of the cell. When a signal arrives at the cell an ion channel opens, allowing sodium ions to flow in, and potassium ions out. This creates a charge difference, and therefore a voltage, and passes the signal along to the next cell.
Electric eels ability to shock their prey relies on this same mechanism. An eel’s electrocytes closely resemble mammalian muscle cells, and work in the same charge-differential, ion-exchanging way, they just have many more muscle cells than us. Each electrocyte produces about 0.15 V, so you can imagine that getting zapped by one of these guys isn’t fun.
So what about bacteria? Well it was first discovered in brewer’s yeast that when bacteria break down carbons (like in the fermentation process) a small amount of electricity is produced. This discovery can be seen at use in microbial fuel cells, which are basically biologically powered batteries!