Electric fish may have switched from AC to DC

[n2doc]

Image of the two new species with graphs of their electric organ discharges (EODs). Brachyhypopomus walteri (top) has a longer, thinner tail and produces an EOD with both positive and negative phases.



Two very similar species of Amazonian electric fish share a key difference: One uses direct current (DC) and the other alternating current (AC), according to research that formally describes the two species for the first time.

The paper was published Aug. 28 in the open-access journal ZooKeys.

Until now, the two types of knifefish were often mistaken for each other and placed together in fish collections. Both communicate with weak electric discharges and "electrolocate" – special receptor cells in their skin can pick up distortions in electric currents made by objects in the water.

The researchers report that one of the species, Brachyhypopomus bennetti, has a large electric organ and a short fat tail and produces direct current, or a monophasic, signal; the other, Brachyhypopomus walteri, has a more typical electric organ, a long thin tail and an alternating current, or biphasic signal.

more
http://phys.org/news/2013-10-electric-fish-ac-dc.html

[dipsydoodle]

1. I think they might mean

alternating DC which stays positive but varies.

I guess if they were fitted with a smoothing capacitor they'd become almost pure DC.

[Wilms]

2. To me, that looks like half-wave rectification.

Have they checked for a diode or two?

[BlueStreak]

3. I suspect this is a japanese science class project that went wrong

Them's fish-bots.