instead of the fish itself, a different class of electroreceptor organs is used for this passive electrolocation, called ampullary organs. Therefore, the black ghost knifefish uses an active and a passive electrosystem, each with its own corresponding receptor organs. The fish can also use a mechanosensory lateral line system, which detects water disturbances created by the motion of the fish's body. As nocturnal hunters, the fish can rely on all three systems to navigate through dark environments and detect their prey. Each species has a characteristic EOD baseline frequency range, which varies with sex and age within the species, as well. The baseline frequency is maintained to be almost constant at stable temperature, but will usually be changed due to the presence of others of the same species. Such changes in frequency relevant to social interaction are called frequency modulations (FMs). The role these FMs have in communication is significant, as black ghost knifefish have developed jamming avoidance responses, which are behavioral responses that avoid the overlapping of EOD frequencies between conspecific individuals to prevent sensory confusion. Moreover, a study was conducted that focused on sexual dimorphism in electrocommunication signals. Female black ghost knifefish generate EODs at a higher frequency than the males, an FM which can be used for gender recognition. A study found the subordinate black ghost knifefish exhibited noticeable gradual frequency rises (GFRs) in their EODs whereas the dominant fish did not, supporting the researchers' hypothesis that GFRs during communication are indicative of submissive signals. It is possible to use a device to convert a captive fish's electrical signals into audible sound, allowing listeners to hear the fish "talk". The Bakken Museum in Minneapolis has a display with such a device and a black ghost knifefish. References . Further reading MacIver M. A., Patankar N. A. & Shirgaonkar A. A. (2010). "Energy-Information Trade-Offs between Movement and Sensing". PLoS Computational Biology 6(5): e1000769. External links Ikan Black Ghost The MacIver Lab Homepage Black Ghost Knife Fish, Apteronotus albifrons (Linnaeus, 1766).BdFISH black ghost knifefish Fish of Venezuela Fish of the Amazon basin black ghost knifefish Taxa named by Carl Linnaeus