Tszzzzzt! Electric fish may jam rivals' signals: Science News Online, Nov. 19, 2005

Tszzzzzt! Electric fish may jam rivals' signals: Science News Online, Nov. 19, 2005: "The brown ghost knifefish (Apteronotus leptorhynchus) generates a weak electric field that it uses to detect obstacles and to communicate with other knifefish. When confronting a rival knifefish, both males and females can raise the frequency of their own electric signals close enough to the other fish's to distort its electric field, reports Sara Tallarovic of the University of the Incarnate Word in San Antonio. In previous experiments, such jamming blinded fish-guidance systems"

Tallarovic and Harold Zakon of the University of Texas at Austin recorded electric frequencies as one knifefish darted in an unfriendly way toward another fish or a dummy emitting an electric signal. The lunger often locked jaws with its opponent or snapped at its electric organ, as if trying to bite it off (view the video clips here).

Decades of experiments had shown that knifefish tailor their electric field frequencies to make them differ from those of a field applied by experimenters, so the idea of intentional jamming has been a surprise, says Tallarovic