ABSTRACT
Electroreceptors are special sensory organs of the lateral line system sensitive to weak electric fields. About one in six of the approximately 55,000 extant vertebrates are electroreceptive. The phylogenetic distribution of electroreception among extant vertebrates indicates a complex evolutionary history with several events. The phylogeny of teleost fishes is characterised by repeated evolution of electroreceptive and electrogenic systems. The ampullae of Lorenzini of cartilaginous fish and the ampullary organs of teleosts are sensitive to low frequency stimulations. The ampullary organs occur on the head, on the rostrum and in some species on the opercula. The Osteoglossomorpha are an unusual group of teleost fishes comprising about 250 species of freshwater fishes, most of which are in one family, the Mormyridae.
