Paris - Sex among electric fish in the Congo River is a rather charged business, according a to new study reporting on an unusual experiment.
Mormyrids are fish that use low-voltage discharges from an electrical organ to hunt for food in chocolate-brown river water.
Intrigued as to how these unusual creatures locate each other for reproduction in almost zero visibility, a German team replicated the mood for mormyrid lurv in a tank on the outskirts of Berlin.
Six females from the species Campylomormyrus compressirostris were shipped in from Kinshasa, capital of the Democratic Republic of Congo.
"All males showed a kink in their anal fin base indicating sexual maturity" the study recounts, a touch breathlessly.
"Prior to the experiments, females were isolated, and breeding conditions were achieved by simulating low conductivity, rainy-season conditions."
Electrical signals
The females, all ready to spawn, were placed at night in the middle of a large tank with a small zone at either end that was sectioned off with a grill.
In a first set of experiments a male was placed in each of the two segregated areas.
One of the males was, like the female, a C compressirostris.
The other was of a closely related species, C rhynchophorus, whose males are physically similar to C compressirostris but send out a much weaker electrical signal.
An infrared camera kept track of the females' movements, and showed - not surprisingly - that the gals were more attracted to their own kind.
In a further set of experiments, the second male came from a third species, C tamandua, whose males are physically quite different to C compressirostris but emit an almost identical electrical signal.
This time, the females showed the same interest in the signals as they did for a male from their own species, suggesting that - as in human love - it's the electricity that counts.
The study, led Ralph Tiedemann of Potsdam University, appears in Biology Letters, published on Wednesday by Britain's Royal Society.
- AFP
