Aside from their properties as biological dynamos, electric eels have other peculiarities; they are not true eels, but are a kind of fish - and a kind of fish that needs to breathe air. The South American predator of river bottoms can reach 40 pounds in size and deliver a fatal shock to humans.They use electricity for a number of purposes other than shocking their prey, as a navigation aid, to communicate with others of its kind and to detect unmoving prey by making its muscles twitch.Martha Foley and Curt Stager discuss the life cycle of a shocking species.