Electroreception is the ability animals have to sense electrical sources. It is mostly found in aquatic or amphibious animals. This is because water helps the signals travel better than air. Some exceptions are the echidnas, cockroaches and bees. Electroreception is used in electrolocation.
Until recently, people thought only vertebrates had electroreception. However, research has shown that bees use electroreception to find flowers. Electroreception is found in lampreys, cartilaginous fishes (sharks, rays, chimaeras), lungfishes, bichirs, coelacanths, sturgeons, catfishes, gymnotiformes, monotremes, and at least one species of cetacean. Fish have electroreception from their lateral lines. In most groups electroreception is used for predation. The Western long-beaked echidna has about 2,000 electroreceptors on its bill. Its relative, the duck-billed platypus, has 40,000.
Electroreceptive animals use this sense to find where objects are. This is important in ecological niches where the animal cannot see. For example, animals cannot use their vision in caves, in murky water, and at night. Many fish use electric fields to find buried prey. Some shark pups "freeze" when they feel the electric signal of their predators.
Images for kids
For the elephantfish (here Gnathonemus) the electric field emanates from an electric organ in the tail region (gray rectangle). It is sensed by the electroreceptive skin areas, using two electric pits (foveas) to actively search and inspect objects. Shown are the field distortions created by two different types of objects: a plant that conducts better than water, above (green) and a non-conducting stone, below (gray).
The platypus also uses electroreception.
Electroreception Facts for Kids. Kiddle Encyclopedia.