At the Shedd Aquarium in Chicago, five eels live in the Amazon Rising habitat, where probes in the water sense their electricity and transmit their energy to a lightbar and a speaker.

At any given time, visitors can hear low-voltage pulsing coming from the speakers. If guests push a button, they can summon bubbles or make it rain in the habitat. The eels become more active, and their electricity increases.

Scientists have long known that electric eels are indeed electric. But in the wild, they are elusive and difficult to study. New habitats like the one at Shedd are allowing researchers to learn more about eels and how they employ their electricity. 

The Elusive Electric Eel

At Shedd, the five eels living in the Amazon Rising habitat are unique in the sense that most aquariums and research centers aren’t able to keep groups.

“Normally, you go places, and you only see one individual,” says Jim Watson, senior aquarist at Shedd Aquarium.

Shedd acquired their five eels when they were young, and Watson says that helped them grow accustomed to each other.

Housing five eels together has the potential to help scientists who study eels to better learn how they interact.

“There’s not a ton known about this animal because they are a little more difficult to research in the wild,” Watson says. 

The eels at Shedd are technically fish, and they belong to the knifefish family. And yes, they are electric. Adult, full-size knifefish are capable of producing up to 800 volts of electricity, Watson says.

Such a jolt could knock a person off their feet or cause fatal disruption to their heart rhythm. When the eels in Watson’s care need medical attention, he says they anesthetize the animal and then monitor their electric output using the probes connected to the lightbar and speaker. Once the eel is safe to handle, they do so wearing insulated gloves. 

“At the aquarium, we’re really careful as to how we handle these animals,” Watson says. 

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How Do Electric Eels Work?

Scientists have long studied how eels were electric, but only in recent years have researchers turned their attention to the eels’ behavior and how they use electricity to communicate, navigate, hunt, and, when necessary, defend themselves.

Eels are able to produce various levels of electrical impulses, depending on what they are trying to accomplish. When hunting, eels emit low-voltage electric waves to navigate and locate their prey. Higher voltage, starting around 400 Hz, is used to attack.

In some situations, prey may be well hidden. Low-voltage emissions cause the prey to involuntarily twitch. The resulting water disturbance reveals their location. When a higher voltage is released, the prey is paralyzed. The eel then suspends the electrical impulses and strikes the prey while it is immobile. However, if the eel misses its mark, the prey has an opportunity to recover and escape. 

Read More: The 5 Senses Animals Have That Humans Don’t

How Powerful Are Electric Eels?

Eels are capable of lifting themselves out of the water to shock a target. In a 2017 article in Current Biology, a researcher willingly made himself the target of such a shocking leap.

The larger the eel, the greater its potential for producing stronger shocks, so the experiment occurred in a laboratory setting with a smaller eel (about 15 inches long). In multiple trials, the researcher put his fist and arm into the top of the tank. In defense, the eel jumped out of the water and onto the researcher’s wrist and arm.

The higher the eel was able to go onto the researcher’s arm, the more forceful the shock. The eel released up to 50 milliamperes (or .05 amperes), and the researcher compared it to touching an electric fence.

At Shedd, the eels are well-fed and have no need to prey upon the others living in their exhibit. “We found that if you put them with certain fish that get used to them, they can sense these pulses as well. The fish around them just move away, so they know,” Watson says.

During feeding times, the eels’ electricity soars due to the activity and excitement. Otherwise, the eels are satisfied and safe, which means they use their electrical impulses for other purposes like navigation and communication.

“They use the low voltage a lot more often as a form of navigation. They are sending out electrical pulses, and they are receiving electrical pulses,” Watson says.                 

Researchers are able to determine whether an eel is using electricity to locate a piece of food based on how the signals change as they approach. Scientists would like to know whether such low-level impulses are also a form of communication between eels.

In the wild, eels typically keep to themselves unless it is mating season. With five eels living in the Shedd habitat, Watson says he’d like to better understand which electrical impulses are consistent with specific behaviors.

Read More: Electric Eels Jump Out of the Water to Intensify Their Shock Power

Article Sources

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Emilie Lucchesi has written for some of the country’s largest newspapers, including The New York Times, Chicago Tribune and Los Angeles Times. She holds a bachelor’s degree in journalism from the University of Missouri and an MA from DePaul University. She also holds a Ph.D. in communication from the University of Illinois-Chicago with an emphasis on media framing, message construction and stigma communication. Emilie has authored three nonfiction books. Her third, “A Light in the Dark: Surviving More Than Ted Bundy,” releases October 3, 2023 from Chicago Review Press and is co-authored with survivor Kathy Kleiner Rubin.