London, Nov 26 : Female elephant nose fish gets sexually 'charged up' by the electric aura of males of their own kind over the spark of closely related species, according to lab experiments.
For a long time, male elephant nose fish are known to lure females with the help of an electric field.
Philine Feulner, a behavioural ecologist at the University of Sheffield, UK, who led the study, said that such electric attraction could maintain genetic differences between the nearly identical fish species.
As compared to electric eels, which deliver 500-volt zaps, elephant nose fish can't muster more than 1 volt and are thus called weakly electric fish.
The fish generate an electric current with an organ in their tail made from specialised muscle cells.
Feulner said that the resulting field helps the long-nosed nocturnal fish to find food and navigate the murky waters of the lower Congo River.
In many closely related species all living in the same vicinity, the jolts differ enough in their length, size, and frequency.
And Feulner and her colleagues managed to easily measure the difference with an electrode inside the fish's aquarium. They could even mimic electric pulses of different species using a simple set-up.
Campylomormyrus compressirostris females spend most of their time near males of their own kind.
While a barrier kept the females from acting on their desires, but that didn't stop fish from releasing eggs after the experiment was complete.
The researchers repeated the experiment with artificial electric fields in place of actual male fish. Again, females lingered near to the same-species signal.
Feulner speculated that the two species of elephant nose fish from the family Mormyridae might still interbreed to produce offspring, but their differing electric fields might keep interspecies sex to a minimum.
This might occur if differences in the strength and duration of electric discharges determine what and where the fish can eat.
According to Matthew Arnegard, an evolutionary biologist at Fred Hutchinson Cancer Research Center in Seattle, Washington, it was a rather good idea.
However more research will be needed to determine whether electric discharges increase species differences - or reflect them.
"That's not really known," New Scientist quoted him as saying.