Curator of Fishes and Biology faculty member Cristina Cox Fernandes helped discover two new species of electric fish (genus Brachyhypopomus). The new species live under "floating meadows," rafts of unrooted grasses and water hyacinth along the margins of the Amazon River. Dr. Cox Fernandes, with colleagues by John Sullivan of Cornell University and Jansen Zuanon of the National Amazonian Research Institute, described the discovery in the open access journal ZooKeys.
The new species are related to South America's famous electric "eel" (not a true eel), which can produce strong electric discharges of hundreds of volts. In contrast, the newly discovered fishes produce pulses of only a few hundred millivolts from an organ that extends into a filamentous tail. Nearby objects in the water distort the resulting electric field, and the distortions are sensed by receptor cells on the fishes' skin. Thus, the fishes use "electrolocation" to navigate through their complex aquatic environment at night. Their short electric pulses, too weak to be sensed by human touch, are also used to communicate with other members of the species.
Dr. Cox Fernandes and her colleagues found that the new species Brachyhypopomus bennetti produces a highly unusual "monophasic" electrical discharge. The only other electric fish in the Amazon with a monophasic discharge is the fearsome electric eel. In their paper, the authors suggest a possible benefit of B. bennetti's distinctive discharge. Unlike the discharges of most other electric fish species, a B. bennetti discharge is largely unaffected if the fish's tail is partially bitten off by a predator (a common type of injury in electric fishes). The researchers suggest that B. bennetti's preference for floating meadow habitat near river channels may put them at particularly high risk of predation and 'tail grazing' by other fishes.
The paper can be accessed here.