It turns out that there is an impressive number of electric eels and that some could emit 1,000 volts.

Shocking fact: not an eel.

Shocking fact: not an eel. (C. David de Santana /)

Do you know what this sound is, Highness? These are electric eels. They are hiding in the freshwater basins of South America, paralyzing their prey by bioelectric shocks that work almost exactly like tasers.

Electrophorus electricus was first identified by Swedish zoologist Carl Linnaeus in 1766 and the shocking fish immediately captivated the collective imagination. In 1806, the famous naturalist Alexander Humboldt reportedly attempted to capture some of the "Die electrischen Fische" by collecting them with his horses. Two of the horses are dead.

For 250 years, scientists have classified the electric eel into a singular species, completely alone in its kind. Everything has changed this week. New results reported in Nature Communications to reveal two additional species: Electrophorus voltai and Electrophorus varii.

With the aid of genetic, morphological and ecological data, scientists have identified three distinct lines of electric eels in the Greater Amazon. Subtle differences in the shape of the head and gills are the only external cues of their diversity. (Alas, none of them screams louder when they are about to feed on human flesh.)

An important point to clarify: electric eels can beshaped, but they are not part of the line of eels. With their smooth, greyish bodies and flat, toothless mouths, electric eels are actually a type of knife-fish, more akin to catfish than to real eels. But they are the only kind of fish-knife that can generate strong electric currents to knock out prey.

One of the species found …Electrophorus voltai– releases the highest bioelectric current ever recorded. When E. voltai flexes his muscles, he generates a truly electrifying 860 volts, making him by far the most powerful generator alive (the previous record holder was his cousin E. electricus with a skinny 650 volts).

"It's such an amazing amount of tension that an organism can grow and unload naturally," says Casey Dillman, co-author of the Cornell University study. For comparison, the wall outlets only provide about 120 volts and you will certainly not see many people strolling, pushing forks into bushings.

But 860 volts is probably not the peak performance of the electric eel. The researchers only examined 107 samples for the new study and they know that longer eels tend to give stronger shocks. Assuming they did not manage to capture a bunch of E. voltai On the upper end of the spectrum of lengths, it is likely that they also have not the highest voltage possible.

"If we added more data points, we would probably discover a stronger discharge," says James Albert, an ichthyologist from the University of Louisiana at Lafayette who did not participate in the study. "I'm sure they would reach over a thousand volts."

The third species, E. varii, provided scientists much less of a literal shock. But there may be an intriguing reason for this: these specimens have been found in the murky lowlands, where the mineral content makes the environment more conducive. So in E. variiFor their part, they need fewer electric shocks to have the same predatory punch. E. voltai returned to the waters slightly less more conductive than is typical for our most popular electric eel species, which could explain why they are spending more energy on their zaps.

Dillman and his colleagues have just started: his team aims to use 21st century techniques to "explore, document and describe" all the knife scams of South America. Their discovery of E. volati and E. varii– which, together, upset centuries of assumptions about an iconic species – only occurred a year after five years of project.

It just reminds us how much it costs. "They are big fish," says Dillman. "They can be six feet long, in some cases. They were hiding at the sight. Despite hundreds of years of explorers, naturalists and taxonomists trying to describe everything on the planet, we still do not have much knowledge, even of these. We do not know how much more we can find once we have really started digging.

But while modern tools and techniques give us the power to investigate these mysteries, our time is running out. Recent years have been marked by extensive land development in South America, which includes the construction of hundreds of gigantic dams. Fires – intentionally caused by farmers and caused by drought – continue to threaten the region. Regardless of whether we can successfully find and catalog an animal before it disappears, says Dillman, most extinctions at this stage are related to human activities. "I think it's a responsibility for which we have a lot of responsibilities," he said.

Eels are currently not in danger of going anywhere. But the Amazon is undoubtedly home to many creatures we have not met yet. According to Albert, it is impossible to know how much our continued development will have an impact on the ecosystem without a complete understanding of the region's biodiversity.

"Nature is a complex puzzle," he says. "You do not always know exactly which piece you have to break before everything collapses."

Kat Eschner contributed to the writing of this article.