The image depicts the electric fish Gnathonemus petersii and a simulation of the field that would be generated if the fish body were electrically transparent. When potential prey approach the fish, electroreceptors in its skin detect pertubations in the electric field, allowing the fish to rapidly detect and locate these nearby objects (See Migliaro et al)

Image Credit: Image by Adriana Migliaro, Ruben Budelli, and Angel Caputi.