The electric eel (Electrophorus electricus) thrives in aquatic ecosystems and is known for its ability to produce electricity. Despite the name, they are not true eels but close relatives of the neotropical knife fish.
One of the most notable electric eel facts is their ability to produce up to 860 volts of electricity. They have integrated this adaptation into their hunting strategy, making them a subject of interest in zoological studies and a noteworthy example of biological diversity.
Related: Find out more about animals whose names start with "E!"
It is a common misconception that electric eels are eels. Despite their physical resemblance to true eels, they are more like electric fish. These freshwater fish belong to a different family known as Gymnotiformes, closely related to the knifefish family.
Electric eels belong to a different order, Anguilliformes, which sets them apart from true eels. Their habitats differ significantly; they reside in freshwater rivers of South America, such as the Amazon and Orinoco. Electric eels lack pectoral fins and have a different tail shape from true eels. Their most distinctive characteristic is their ability to generate electricity5, which is absent in true eels.
While electric eels' bodies can reach up to 8 feet long, their vital organs, including the heart, lungs, and digestive system, are just a fifth of their body. They all fit in a space near their heads. This compact layout is a strategic adaptation that has evolved over millions of years.
Meanwhile, the rest of their bodies contain three electric organs: the Sachs, Main, and Hunter's organ. These organs generate the electricity electric eels use to communicate4.
These organs are full of electrolytes that work together to generate the electrical discharge that eels use for hunting, navigation, and self-defense.
In addition, even their skin contains sensitive electroreceptor cells, which allow them to detect tiny electric fields in the water. This ability acts as a sixth sense, helping them to locate prey or sense changes in their environment.
Another fact about electric eels is that they have poor eyesight but can navigate their surroundings through electroception, sending out electrical pulses to feel their way around2.
Swimming in murky, muddy waters relies on high-voltage pulses as their primary means of navigation. The electric eel emits a low-voltage electric field that envelops its body, providing an invisible cloak of electricity. When a creature or object enters this field, it causes a disruption that breaks the field, alerting the eel to the intruder's presence.
Using this ability, the eel meticulously processes these disruptions into valuable insights about the intruder, including size, shape, and distance. This system is akin to a biological radar system, powered entirely by electricity and a lifeline for the eel.
The electric eel has captured the attention and imagination of scientists and curious individuals due to its impressive abilities. The Electrophorus electricus is traditionally recognized for its electricity production capability1. However, in 2019, biologists discovered two other electric eels: the Electrophorus varii and the Electrophorus voltai.
The main feature of the Electrophorus voltage is its ability to discharge an 860-volt electric shock. It lives in the high-altitude waters of the Amazon and has evolved to produce the highest voltage ever recorded from a living creature, exceeding the previous 600-volt record. Due to the low conductivity of its habitat, this electric eel's shock helps it stun prey and fend off predators.
Related: Learn more about how the electric eel influenced the study of electricity in our post on electricity facts.
Electric eels are territorial, carefully guarding their territory against intruders. This behavior comes from an instinctual urge for survival rather than shyness. Moreover, electric eels only come together to mate, with male and female electric eels returning to solitude afterward.
Additionally, electric eels are nocturnal creatures that retreat into hiding spots during daylight hours. They emerge to hunt and feed at night, using their potent electric charge to catch unsuspecting prey. However, when prey is abundant, the eels may form short-lived alliances to hunt together.
Fun electric eel fact: Did you know electric eels need to breathe air because they have no gills?
The electric eel can leap out of the water3, which Ken Catania, a biologist from Vanderbilt University, discovered. Catania encountered this surprising skill while experimenting with a metal rod and an eel-filled tank.
When he pulled the rod closer, the eels flexed their muscles and sprang out of the water towards the rod, showing more enthusiasm towards conductive materials than non-conductive materials.
Moreover, the eels would bend their necks as they leaped out of the water to ensure maximum contact with their target and electrical transfer. Catania made these observations and provided insight into electric eels' behavior and abilities.
The electric eel has developed a unique strategy that resembles a martial arts technique, which allows them to survive during dry seasons. Due to limited water, the eels often find themselves in small ponds. To combat this issue, they jump out of the water to deliver powerful shocks to their prey, whether under or above it.
Carl Linnaeus, the father of modern taxonomy, was the first to describe the electric eel in 1766 formally. His work spotlighted this unusual creature, sparking curiosity in the scientific community.
Around ten years later, the American academic Hugh Williamson threw his hat in the ring, publishing an in-depth paper in 1775 titled "Experiments and Observations on the Gymnotus Electricus, or Electric Eel." His work peeled back the layers on the eel's ability to generate electric shocks. In addition, the Scottish surgeon John Hunter also studied electric eels and rays.
These individual research projects gathered sufficient knowledge to inspire impressive scientific advancements, like the invention of the first battery. These studies helped Alessandro Volta brainstorm the ideas that led to the creation of the voltaic pile in the late 18th century.
In a fitting tribute to this intertwined history, a newly discovered species of electric eel was christened Electrophorus voltai in 2019.
Male electric eels display a unique behavior during the breeding season, producing a particular type of dense saliva and releasing it into the water. Then, the eel stirs the saliva around to create a foamy structure, expanding to a meter in diameter. This structure is the saliva nest and is a pivotal component in the mating process of electric eels.
The saliva nest protects the female electric eel's eggs from potential predators. The nest can hold up to 17,000 eggs, which sit under the guard of the male eel. After two to three days, the eggs hatch, and the newborn eels remain in the nest until they are strong enough to survive in the outside world. Over time, the saliva nest disintegrates.
Electric eels display fascinating characteristics even before their birth. They develop rudimentary versions of three significant organs - the main organ, Hunter's, and Sach's - from an early stage.
The primary and Hunter's organs generate high-voltage shocks, while the Sach's organ emits low-voltage pulses, which help the young eels navigate and communicate. As the eels mature, their electrolytes become stronger and more efficient, promising stronger electric outputs.
The electric eel is a predator that thrives in South America's Amazon and Orinoco rivers. Due to the largely undisturbed nature of these waterways, electric eels have found optimal conditions for their survival. Studies and local reports suggest that their population is relatively stable.
However, the eels are not immune to threats. Human activities, such as deforestation and pollution, are altering the quality of the water and the landscapes of the Amazon, threatening their habitats.
Despite their reputation as dangerous creatures, electric eels are not a preferred target of local hunters. However, some reports of an increased prevalence of people hunting electric eels for the aquarium trade suggest they are not entirely safe. Meanwhile, many regions have legislation that prevents people from keeping electric eels due to concerns about their impacts on local fish populations should they escape.
Nevertheless, unintentional protection may be necessary in the face of global climate change, which can gradually impact freshwater ecosystems and potentially affect the eel populations in unforeseen ways.
Currently, no specific conservation programs focus on the electric eel. However, the Amazon rainforest is a biodiversity treasure trove, and efforts to protect this resource indirectly defend the electric eel species.
de Santana, C. D., Crampton, W. G. R., Dillman, C. B., Frederico, R. G., Sabaj, M. H., Covain, R., ... & Lundberg, J. G. (2019). Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator. Nature Communications, 10(1), 1-12.
Catania, K. C. (2015). Electric eels concentrate their electric field to induce involuntary fatigue in struggling prey. Current Biology, 25(22), 2889–2898.
Catania, K. C. (2016). Leaping eels electrify threats, supporting Humboldt’s account of a battle with horses. Proceedings of the National Academy of Sciences, 113(25), 6979-6984.
Gallant, J. R., Traeger, L. L., Volkening, J. D., Moffett, H., Chen, P. H., Novina, C. D., ... & Sussman, M. R. (2014). Genomic basis for the convergent evolution of electric organs. Science, 344(6191), 1522-1525.
Catania, K. (2014). The shocking predatory strike of the electric eel. Science, 346(6214), 1231-1234.