The ability to generate electricity is a fascinating biological phenomenon. While the term “eel” often brings to mind creatures that can deliver an electric shock, most eels do not possess this capability. Only electric eels have evolved specialized organs to produce significant electrical discharges.
Understanding Electric Eels
The species most renowned for its powerful electric shocks are the electric eels, belonging to the genus Electrophorus. Despite their common name, these fish are not true eels, which are classified under the order Anguilliformes. Instead, electric eels are a type of knifefish, more closely related to catfishes and carp, and are part of the order Gymnotiformes. There are three recognized species within the Electrophorus genus: Electrophorus electricus, Electrophorus voltai, and Electrophorus varii. These unique fish are native to the freshwater systems of South America, primarily found in the Amazon and Orinoco river basins. They typically inhabit slow-moving, murky waters such as pools, swamps, and oxbow lakes. Electric eels are obligate air-breathers, needing to surface frequently to gulp air, an adaptation that allows them to thrive in oxygen-poor environments.
How Electric Eels Generate Power
Electric eels generate electricity using specialized organs, which can constitute up to 80% of their body and are composed of thousands of modified muscle cells called electrocytes or electroplaques. These disc-shaped cells are arranged in stacks, similar to a series of batteries, enabling the eel to produce a cumulative voltage. When discharging, the eel’s brain sends a nerve signal to the electrocytes. This triggers a rapid change in cell membrane permeability, causing positively charged sodium ions to flood into the cells and potassium ions to flow out, creating an electrical potential, and the synchronized discharge of thousands of electrocytes then generates a powerful current. Electric eels utilize three main electric organs: the main organ and Hunter’s organ produce strong shocks for defense and stunning prey, while the Sach’s organ generates weaker pulses for navigation and communication.
Impact of an Electric Eel Shock
The most powerful species, Electrophorus voltai, can generate up to 860 volts, while Electrophorus electricus and Electrophorus varii produce around 480 to 572 volts. The current delivered can be up to 1 ampere. When a human experiences a shock, it is described as a strong jolt followed by muscle spasms and a sensation of numbness, rather than a burning pain.
While a single shock is rarely fatal to humans, it can be intensely painful and debilitating. The main danger comes from secondary effects; a person might be temporarily paralyzed or incapacitated, leading to drowning, even in shallow water. Multiple shocks, which an eel can deliver in rapid succession, can potentially lead to respiratory failure or cardiac arrest. Electric eels can even leap partially out of the water to deliver a more concentrated and powerful shock to a perceived threat, a behavior strong enough to deter large animals.
Encountering Electric Eels Safely
Electric eels are not aggressive and use their powerful electric discharges only when threatened or hunting prey. Their poor eyesight means they rely on weak electric pulses for navigation and to locate objects in their murky habitats. To safely coexist, avoid their habitats, especially during dry seasons when low water levels may concentrate eels. If in areas where electric eels are present, avoid touching or provoking any aquatic animal. Remember that they can deliver a shock even when partially out of the water, making direct contact especially risky.