Can An Electric Eel Kill You?

By D.C. Demetre •  Updated: 08/08/22 •  8 min read

Can you be killed by an electric eel? A shock from an electric eel would not kill a healthy human directly. Being stunned by its shock could be enough to immobilize someone and result in a fall leading to drowning, even in shallow water. And getting more than one shock could make a person with a weak heart experience heart failure.

The shock from an electric eel only lasts around two-thousandths of a second, but the strongest species- Electrophorus voltai – can produce a shock of up to 860 volts. The other species generate from 400-650 volts. The current, however, is low, around 1 amp – the equivalent of the amperage of a typical two-battery flashlight.

In comparison, a shock from a wall power outlet can be 10 or 20 amps. The electric eel does not produce a direct current but an alternating current (in pulses), and its charge is depleted after a strong shock.

How Do Electric Eels Work?

Electric eels are not true eels, but freshwater knifefish that are related more closely to catfish than eels. They are electric, however. They produce electricity to stun prey, defend themselves and communicate with other fish.

All animals with a nervous system are electric to some extent. It is how nerves carry messages around our bodies to do things like trigger our heartbeats, keep our lungs breathing and keep our cells functioning.

Electric eels are unique because they can produce high voltage electrical discharges they shoot into the water. The voltage comes from hundreds of thousands of specialized muscle cells called electrolytes.

These cells are located in the animal’s mouth and along its body in three pairs of electric organs – the main organ, Hunter’s organ, and Sachs’ organ. As with muscle cells, the electric eel’s electrocytes contain the proteins actin and desmin, but where muscle cell proteins form a dense structure of parallel fibrils, in electrocytes, they form a loose network.

Electric eel's electric organs

An electric eel’s electric organs. Credit: Chiswick Chap CC-BY

 

Each cell only produces a small amount of electricity, around 150 mV. But the electric eel’s main organ contains stacks of 6000 electrocytes in series; the organ has about 35 of these stacks in parallel, on each side of the body.

When the electric eel needs to produce an electric charge, it sends a signal to these cells, opening ion channels. This allows sodium to flow through, reversing the polarity briefly. The sudden difference in electric potential generates an electric current like a battery, in which cells are also stacked to produce a desired total voltage output.

The electric eel’s Sach’s organ is used for electrolocation. It senses its environment by generating a weaker electric field (around 10 volts) and detecting distortions in these fields using electroreceptor organs. It is similar to how a bat can “see” its environment through sound waves.

The exact function of its third organ, Hunter’s organ, is unknown, but it appears to work alongside the main organ to produce high voltage shocks.

How Electric Fish Evolved

Electrified organs enable electric fish, like electric rays, elephantfishes, electric catfishes, and electric eels, to do all kinds of astonishing things. They send and receive signals similar to bird songs, helping them recognize other electric fish by species, sex, and even individual.

Evolution exploited a peculiarity of fish genetics to develop electric organs. All fish have replica versions of the same gene that produces tiny muscle motors, called sodium channels. To evolve electric organs, electric fish turned off one duplicate of the sodium channel gene in muscles and turned it on in other cells.

Electrophorus varii

Electrophorus varii. Credit: D. Bastos

 

Recent research has found a short section of this sodium channel gene — about 20 DNA letters long — that controls whether the gene is expressed in any given cell. In electric fish, this control region is either altered or entirely missing. And that’s why one of the two sodium channel genes is turned off in the muscles of electric fish.

The University of Texas at Austin’s professor Harold Zakon, one of the study’s authors, noted that its implications go far beyond the evolution of electric fish.

“This control region is in most vertebrates, including humans. So, the next step in terms of human health would be to examine this region in databases of human genes to see how much variation there is in normal people and whether some deletions or mutations in this region could lead to a lowered expression of sodium channels, which might result in disease,”

Zakon said.

There are two groups of electric fish in the world.

The researchers discovered that the electric fish in Africa had mutations in the control region, while electric fish in South America lost it entirely. Both groups arrived at the same solution for developing an electric organ — losing expression of a sodium channel gene in muscle — though from two different paths.

Where Are Electric Eels Found?

where do electric eel live

Habitats for the three species of Electrophorus in the north of South America. Credit: Carlos David de Santana & al. CC-BY

 

There are three species of electric eel that are found in different areas. Electrophorus electricus inhabits the far north of Brazil, in a region called the Guiana Shield, the northern areas of three Brazilian states (Amapá, Amazonas and Roraima), and Guyana, French Guiana and Suriname.

Electrophorus voltai inhabits the Brazilian Shield, which encompasses the south of Pará state and Amazonas state, as well as Rondônia and the north of Mato Grosso. Shield regions are relatively elevated, exceeding 300 meters in altitude.

The region’s rivers feature rapids and waterfalls, with clear, well-oxygenated water, rocky or sandy bottoms, and low amounts of dissolved salts. These characteristics favour both species, which have flat heads that help them swim nimbly and hunt in fast-flowing water over stony riverbeds.

The low amount of salts makes the water less electrically conductive. Researchers believe the animals need to produce more substantial discharges to capture prey. This is particularly the case for E. voltai, which was found to deliver the highest voltage ever recorded in an animal.

Electrophorus varii, by comparison, inhabits the lowest part of the Amazon Basin, living in muddy rivers with relatively little oxygen and sandy or muddy bottoms. In addition, the larger amount of dissolved salts increases the conductivity of the water, favouring the propagation of their electrical discharges, which in this species range from 151 volts to 572 volts.

When Was The First Electric Eel Discovered?

Interestingly, this 2019 study also found that electric eels communicate with each to summon groups that can electrocute a potential threat. Counter to what earlier science had believed to be accurate, these are not solitary animals – they often associate in groups of up to ten as adults.

However, the existence of electric fish was known to man long before Linnaeus. There are drawings of electric catfish on tombs from Ancient Egypt, and descriptions of torpedo rays from Classical Greece.

Brazilian indigenous tribes were aware of these river eels as well. In the Tupi language, they called electric eels ‘poraquê’, which meant “that which makes sleep” or “that which numbs”, and the term is still used today in Brazil to describe eels from Amazonian rivers.

Sources:

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  3. de Santana, C.D., Crampton, W.G.R., Dillman, C.B. et al. Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator. Nat Commun 10, 4000 (2019).
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