The electric eel is one of the few animals that hunts with a weapon most people associate with power lines. Lurking in the murky, oxygen-poor waters of South America, it can generate a jolt of electricity strong enough to stun a fish, deter a predator, or leave a wading person badly shaken. The strongest members of the genus are capable of discharges reaching roughly 860 volts, among the most powerful bioelectric output known in nature.
Despite the name, the electric eel is not a true eel at all. It belongs to a group of South American fish called knifefishes, and its resemblance to an eel is a matter of body shape rather than kinship. Its electrical abilities have fascinated scientists since the eighteenth century, when early studies of the fish helped inspire one of the most important inventions in the history of technology.
A knifefish, not an eel
Electric eels make up the genus Electrophorus, freshwater fish native to northern South America. For more than two centuries the genus was thought to contain a single species, but in 2019 researchers divided it into three, distinguished by DNA, anatomy, ecology, and electrical strength. According to the study describing the split, one of the newly named species, Electrophorus voltai, is the strongest bioelectricity generator ever documented, producing discharges of up to 860 volts, well above the roughly 600 volts long attributed to the classic electric eel. The animals grow throughout their lives, adding vertebrae as they lengthen, and can reach two meters and 20 kilograms, with some captive specimens living more than 20 years.
Living batteries of stacked cells
An electric eel’s power comes from specialized organs that fill much of its long body. These are packed with thousands of modified muscle cells called electrocytes, arranged in stacks much like the cells of a battery. Each cell produces only a small voltage, but because they are wired in series, their outputs add together into a single formidable discharge. The fish maintains separate systems for different tasks: high-voltage bursts for hunting and defense, and weaker signals used to sense the world around it. That layered design lets the animal switch between stunning prey and quietly feeling out its surroundings. The electric organs run down most of the eel’s length, occupying the majority of its body, while the vital organs are packed into a small region near the head. Research has shown that when an eel discharges near hidden prey, the burst can trigger the prey’s muscles to twitch, revealing its position and letting the eel home in on a target it cannot see in the dark, turning the same jolt into both a weapon and a search tool.
Hunting by shock in dark water
Electric eels are nocturnal and have poor eyesight, so they rely heavily on electroreception, sensing the tiny electrical fields around them, to navigate and locate prey in the shade and mud where they live. When it finds a target, the eel unleashes a high-voltage volley that causes the prey’s muscles to seize involuntarily, immobilizing it long enough to be swallowed. Observers have documented E. voltai hunting cooperatively, with groups herding shoals of small fish into tight balls before launching coordinated strikes, behavior that is unusual among fish and suggests the shocks serve as more than a simple ambush tool.
Surviving where the water runs low on oxygen
The three species occupy largely separate ranges across northern South America, from the upland waters of the Guiana and Brazilian shields to the seasonally flooded lowlands. They favor muddy river bottoms, swamps, and deeply shaded pools, environments that are often low in dissolved oxygen. Electric eels cope by breathing air: they are obligate air-breathers that must surface periodically to gulp oxygen, an adaptation that lets them thrive in stagnant water where many fish would suffocate. Their diet centers on other fish, including armored catfishes, and at least one specimen was found to have eaten a caecilian, a legless amphibian with toxic skin secretions, hinting that the eels may be resistant to such defenses. The 2019 division of the genus into three species tracked these ecological differences closely: the northern species keeps to the upland waters of the Guiana Shield, the powerful E. voltai ranges from the Brazilian shield northward, and the central species occupies the lowlands, where water levels swing dramatically between wet and dry seasons. That the most powerful discharges belong to an upland species has led some researchers to suggest that clearer, faster-moving water may favor the evolution of stronger shocks.
The fish that helped inspire the battery
The electric eel’s influence reaches into the history of physics. Its electrical capabilities were first studied scientifically in 1775, and the fish’s stacked, cell-by-cell method of building up a charge is often credited as an inspiration for Alessandro Volta, whose voltaic pile, the first true electric battery, appeared in 1800. The species name of the most powerful electric eel, voltai, honors that connection directly. Centuries after those early experiments, the animal remains a striking reminder that living tissue discovered how to generate and deploy electricity long before humans learned to harness it.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
More from Morning Overview
