Electric Eel

Despite the common name, the electric eel is not a true eel but a member of the knifefish order, native to the slow-moving rivers, floodplains, and swamps of the Amazon and Orinoco basins in South America. It is famous for generating powerful electric discharges, reaching several hundred volts, produced by specialized electric organs that make up most of the length of its body. These discharges serve multiple functions, including stunning prey, navigation through electrolocation, and defense against predators. Recent research has split what was long considered a single species into three distinct species within the genus Electrophorus, distinguished by habitat and the strength of their electric discharge.

Electric eels are identified by their eel-like shape and lack of a dorsal fin.

• Body: elongated, cylindrical, 2-2.5 m typical adult length, with tiny embedded scales giving a smooth appearance
• Fins: no dorsal fin; a long, undulating anal fin runs along nearly the entire underside and is the main means of propulsion
• Head: blunt and rounded, small eyes
• Color: dark olive-brown dorsal surface with a contrasting yellow-orange throat and chin
• Behavior cue: must surface periodically to gulp air, unlike most fish

Look-alike: unlike true eels (order Anguilliformes), electric eels lack a dorsal fin and belong to an entirely different order.

Electric eels inhabit slow-moving freshwater rivers, floodplain pools, and swamps with low oxygen levels throughout the Amazon and Orinoco river basins of South America. They are obligate air-breathers, using a highly vascularized mouth lining to extract oxygen directly from air, which allows them to survive in warm, oxygen-poor, often turbid water where many other fish cannot persist. Because of this adaptation, they must surface every few minutes to gulp air even in otherwise suitable water. Their habitat typically includes dense aquatic vegetation and submerged structure offering cover, particularly in floodplain habitats that expand seasonally with rainfall.

Electric eels generate strong electric pulses using specialized electric organs that occupy most of their body length, employing high-voltage discharges to stun prey and lower-voltage pulses for navigation and detecting objects through electrolocation in murky water. They are primarily nocturnal hunters, feeding on fish and other small vertebrates using a rapid strike aided by their electrical stunning ability. As obligate air-breathers, they surface regularly to gulp air regardless of water oxygen levels. Electric eels are generally solitary, and males are known to build nests from foam and saliva-like secretions, guarding the eggs and young within them. Their electric discharges also play a defensive role against potential predators.