Electrophorus electricus

Electrophorus electricus
Electric eel at the New England Aquarium, United States
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Gymnotiformes
Family:	Gymnotidae
Genus:	Electrophorus
Species:	E. electricus
Binomial name
Electrophorus electricus (Linnaeus, 1766)
Synonyms
Gymnotus electricus

Electrophorus electricus is the best-known species of

In September 2019, David de Santana et al. suggested the division of the genus into three species based on DNA divergence, ecology and habitat, anatomy and physiology, and electrical ability: E. electricus, E. voltai sp. nov., and E. varii sp. nov. The study found E. electricus to be the sister species to E. voltai, with both species diverging during the Pliocene.^[2]

Anatomy

E. electricus has an elongated,

E. electricus has a vascularized respiratory system with gas exchange occurring through epithelial tissue in its buccal cavity.^[7] As obligate air-breathers, E. electricus must rise to the surface every ten minutes or so to inhale before returning to the bottom. Nearly eighty percent of the oxygen used by the fish is obtained in this way.^[8]

Physiology

E. electricus has three pairs of abdominal organs that produce electricity: the main organ, Hunter's organ, and Sachs' organ. These organs occupy a large part of its body, and give the electric eel the ability to generate two types of

Electric eels use electricity in multiple ways. Low voltages are used to sense the surrounding environment. High voltages are used to detect prey and, separately, stun them, at which point the electric eel applies a suction-feeding bite.^[12]

Sachs' organ is associated with

The typical output is sufficient to stun or deter virtually any animal. The eels can vary the intensity of the electric discharge, using lower discharges for hunting and higher intensities for stunning prey or defending themselves. They can also concentrate the discharge by curling up and making contact at two points along its body.[16] When agitated, they can produce these intermittent electric shocks over at least an hour without tiring.^{[citation needed]}

E. electricus also possesses high frequency–sensitive tuberous receptors, which are distributed in patches over its body. This feature is apparently useful for hunting other Gymnotiformes.^[13] E. electricus has been prominent in the study of bioelectricity since the 18th century.^[17] The species is of some interest to researchers, who make use of its acetylcholinesterase and adenosine triphosphate.^[18][19]

Despite being the first described species in the genus and thus the most famous example, E. electricus actually has the weakest maximum voltage of the three species in the genus, at only 480 volts (as opposed to 572 volts in E. varii and 860 volts in E. voltai).^[2]

Ecology and life history

Habitat

E. electricus is restricted to freshwater habitats in the Guiana Shield. Populations in the Amazon basin, Brazilian Shield, and other parts of the Guiana Shield are now thought to belong to E. varii and E. voltai.^[20]

Feeding ecology

E. electricus feeds on invertebrates, although adult eels may also consume fish and small mammals, such as rats. First-born hatchlings eat other eggs and embryos from later clutches.^[13] The juveniles eat invertebrates, such as shrimp and crabs.

Reproduction

E. electricus is known for its unusual breeding behavior. In the dry season, a male eel makes a nest from his saliva into which the female lays her eggs. As many as 3,000 young hatch from the eggs in one nest. Males grow to be larger than females^[21][22] by about 35 cm (14 in).^[23]

References