Electric eels, inhabitants of South American freshwaters, are capable of generating powerful electric shocks. This ability is exclusive to specific species within the genus Electrophorus. While commonly referred to as eels due to their elongated bodies, these creatures are not true eels in the biological sense; they are a type of knifefish more closely related to carp and catfish.
How Electric Eels Generate Power
Electric eels produce electrical discharges through specialized organs that occupy up to 80% of their body length. These organs, including the main organ, Hunter’s organ, and Sachs’ organ, are composed of thousands of modified muscle cells called electrocytes, stacked in series, similar to a biological battery. Each electrocyte generates a small voltage, around 0.15 to 0.185 volts, and these individual charges combine to create a higher overall voltage.
The process of electricity generation involves the rapid movement of ions, particularly sodium, across the cell membranes of these electrocytes. When the eel’s brain signals these cells, ion channels open, causing a sudden flow of positively charged ions and creating an electrical potential difference. This arrangement allows for synchronized discharge, producing low-voltage pulses for navigation and communication, and high-voltage bursts for stunning prey or deterring predators. Some species, like Electrophorus voltai, can generate shocks up to 860 volts, making them the strongest bioelectricity generators.
The Effect of an Electric Shock
An electric eel’s shock results in intense pain, involuntary muscle spasms, and temporary numbness. While a single jolt is rarely fatal to a healthy adult, it can be incapacitating. The main danger comes from secondary effects like temporary paralysis or loss of balance, which can lead to drowning, even in shallow water.
Multiple or prolonged shocks can pose more significant risks, potentially causing respiratory distress or heart failure, especially in individuals with pre-existing heart conditions. Historically, large electric eels have incapacitated animals like horses. Shock intensity varies by the eel’s size, species, and contact duration, but even smaller eels deliver a substantial jolt.
Distinguishing Electric Eels
This trait is specific to the genus Electrophorus, which comprises three recognized species: Electrophorus electricus, Electrophorus voltai, and Electrophorus varii. These species were identified in 2019, distinguishing them from what was previously thought to be a single species.
Despite their common name, electric eels are scientifically classified as a type of knifefish within the order Gymnotiformes, meaning they are not closely related to true eels of the order Anguilliformes, such as moray eels. True eels, like moray eels, do not possess electric organs and cannot generate electric shocks. Electric eels are freshwater fish found exclusively in the Amazon and Orinoco river basins of South America, preferring slow-moving, murky waters.