8 Shocking Facts About Electric Eels

The face and head of a gray colored electric eel with a pink mouth

Reinhard Dirscherl / Getty Images

The electric eel is not an eel at all, it’s a fish. Their long, slender bodies give them the appearance of an eel, but their ability to deliver a high voltage jolt of electricity is uniquely their own. The three species of electric eels each occupy unique regions within South America. They are all top predators, with little to fear in their habitats.

From their ability to leap from the water to attack prey to their highly complex sensory system, discover the most fascinating facts about electric eels.

1. Electric Eels Aren't Eels

Despite its misleading common name, the electric eel is a South American species of knifefish and is closely related to catfish. It’s so unique that it has its own genus: Electrophorus. For centuries, scientists believed there was only one species of electric eel, but in 2019 researchers using DNA analysis discovered that there are actually three distinct species: Electrophorus voltai, Electrophorus varii, and Electrophorus electricus. Each species inhabits a different region — the electricus is found in the Guiana Shield, the voltai is in the Brazilian Shield, and the varii inhabits the lowland Amazon basin. They are all similar in appearance, except that the voltai has a more egg-shaped head than the other two.

Though they aren’t eels, they have an elongated, cylindrical, snake-like appearance, just like true eels. Unlike eels, electric eels are freshwater fish that spend most of their time at the bottom of muddy rivers and streams.

2. They Deliver Quite a Shock

Electric eels come by their name for good reason — depending on the species, they can release an electric shock of up to 860 volts. This defense mechanism is created by three organs found in all three electric eel species: the main organ, the Hunter’s organ, and the Sach’s organ. The strongest electrical discharges are caused by the main and Hunter’s organs working in unison, while the Sach’s organ produces lower voltage electrical charges.

Scientists discovered that the strongest high voltage charges, up to 860 volts, come from the Electrophorus voltai species, while the Electrophorus electricus and Electrophorus varii produce high voltage charges of up to 480 volts and 572 volts, respectively.

3. They Can Leap Out of the Water

Not only are electric eels capable of delivering a high voltage shock, but they are also known to leap out of the water to attack predators. Vanderbilt University biologist Ken Catania inadvertently made the discovery while handling electric eels in a tank using a net with a metal rod. He observed that when the metal rod approached, the eels lunged up from the water to attack it with electric shocks.

Because the rod conducts electricity, the eels saw it as a large animal. When nonconductors were used, the eels ignored the target and did not attack. In the same study, the eels bent their necks to keep in contact with the target, ensuring whatever predator they’re defending against feels their full wrath. While the electric eel is a top predator that has little to fear in the wild, this strategy is especially beneficial during the dry season when the eels may be stuck in small ponds and particularly vulnerable.

4. They Lay Eggs in Nests of Saliva

During the dry season, female electric eels lay their eggs in a foam nest made of saliva. Males are responsible for building the nest of spit and guarding the eggs until they hatch during the rainy season. An average of 1,200 baby eels will hatch from the well-guarded nest. Electric eels are believed to be fractional spawners that lay three batches of eggs during each spawning cycle.

5. They Are Mouth-Breathers

An electric eel on the bottom of a tank surrounded by green underwater plants
 wrangel / Getty Images

While they have small gills on the sides of their head, electric eels get most of their oxygen at the water’s surface. Electric eels obtain around 80% of their oxygen by gulping air with their mouths — an adaptation for the muddy, poorly oxygenated waters in which they live. Since electric eels are obligatory air breathers, they must come up for air to survive.

6. They Use Their Electric Charge Like Radar

Because they have poor eyesight and live in a muddy environment, electric eels have been adapted to use their electric power for another purpose — locating fast-moving prey. A study of the electrical pulses discharged by electric eels revealed that there are three distinctive types. The eels utilize a low voltage pulse for electrolocation; short, high-voltage pulses for hunting; and the highest frequency and intensity pulses when they are in attack mode.

After delivering a shock to their prey, the eels will follow the electric field like a radar, zeroing in on their incapacitated prey without using sight or touch.

7. They Curl up to Concentrate Their Shocking Powers

Electric eels use a clever strategy to handle large or challenging prey. They curl around it, holding the prey near their tails — which are essentially two electric poles. At a minimum, this strategy doubles the electricity and thus the amount of shock the prey receives. This behavior is particularly effective because it allows the eels the chance to immobilize and reposition prey so that it can be easily consumed.

8. They Are Mostly Comprised of Electric Organs

While electric eels can reach a body length of up to 8 feet, only 20% of that length contains their vital organs. The eel’s entire posterior, 80% of its body, is electric organs. Even their skin is covered by tuberous and ampullary electroreceptor cells. All of their internal organs are squeezed into the small space near their head.

View Article Sources
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  3. Catania, Kenneth C. "Electric Eels Use High-Voltage To Track Fast-Moving Prey." Nature Communications, vol. 6, no. 1, 2015, doi:10.1038/ncomms9638

  4. Catania, Kenneth C. "Electric Eels Concentrate Their Electric Field To Induce Involuntary Fatigue In Struggling Prey." Current Biology, vol. 25, no. 22, 2015, pp. 2889-2898., doi:10.1016/j.cub.2015.09.036

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