There are two ways that animals use electroreception. They either use their own electric currents and sense how those currents bounce back to interpret their surroundings. Or they pick up the electric currents already being produced by other animals to locate prey. Electroreception is most common in fish and some amphibians because salt water is a fantastic conductor of electricity – especially compared to air.
But, sharks are truly some of the best at using electroreception because they’re so sensitive. In addition to their strong muscles, aerodynamic shape, and specialized fins, this sixth sense helps sharks to be the talented hunters that they are famous for. Great white sharks are so sensitive, they can detect one millionth of a volt in a centimeter of seawater and maybe even less than that.
As a shark swims through the water, these electric fields travel into the pores under its head, through the tubes to the ampullae. Then tiny hairs read these signals and use a network of nerves to send a message to the brain. This gives the shark exact dimensions and location of the fish, helping catch and eat it.