Electric eels might be the stuff of nightmares for some, but are they really electric – and do they have the power to give you a painful zap? We break down just watt makes these eels so shocking. 

What is an electric eel?

Electric eels are one of three species in the genus Electrophorus. They belong not to the “true” eels in the order Anguilliformes – which contains everyone's favorite the moray – but to a different order called Gymnotiformes, also known as the knifefishes. With slender bodies and tapered tails, electric eels are more closely related to carp and catfish. 

Electric eels are beefy, with bodies that can measure 2.5 meters long (8 feet), and weigh 20 kilograms (45 pounds). These eels live in and around the Amazon and the Orinoco basin in South America. While they possess gills, electric eels are air breathers and receive 80 percent of their oxygen through their mouths. 

How do electric eels generate electricity?

Their impressive bodies also house three snazzy organs that help the fish create their own electricity. These are called the main organ, the Hunter’s organ, and the Sach’s organ; they also contain around 6,000 specialized cells called electrocytes. These electrocytes can discharge power simultaneously when the fish is under threat or attacking prey of its own. 

“Electric eels are like living batteries,” explains Dr Rupert Collins, Senior Curator of Fishes at the Natural History Museum, London. “They have stacks of modified muscle cells called electrocytes that have both a positive and a negative side. When the cells are triggered, it discharges an electrical impulse into the surrounding water.”

So how can an electric eel shock prey but not shock itself in the process? Well, nobody really knows for sure but the best guess is that the water surrounding the eel absorbs most of the current generated by the cells. The current also only flows for around 2 milliseconds, making it likely not long-lasting enough to do damage to the eel itself. 

Typically, eels generate around 600 volts of electricity, but a discharge of 860 volts was recorded from one study, both of which are enough to kill a human. Deaths from electric eel shocks are extremely rare but multiple shocks can cause respiratory difficulties and even cause your heart to stop. This, added to the fact that you're likely in the water when faced with an eel, adds to the other life-threatening problem of drowning, if the eels don’t get you first, the water might.