The electric eel (Electrophorus electricus) is a freshwater fish that belongs to the Electrophoridae family. Its body is elongated and it has a long and wavy anal fin, which is located along the inside, up to the tail. This species lacks dorsal and pelvic fins.
The most outstanding feature is its ability to be a bioelectric generator, being able to discharge a direct current from 600 volts to 1 watt. This occurs due to the active transport of potassium ions, through the electrocyte cells that make up its three electrical organs..
When the eel locates a prey, the brain sends a signal to the electrocytes, causing the sodium ions to flow and causing the cell's polarity to reverse momentarily..
The sudden difference in electric potential generates an electric current, similar to that of a battery, where the plates that are stacked cause a difference in electric potential.
This produced energy is used by the eel to stun its prey, for navigation and for defense.
Electrophorus electricus it is an endemic fish of the South American neotropical region. Inhabits calm and shallow waters of the Orinoco and Amazon rivers.
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The body has an elongated and cylindrical shape. The head is flattened, with a large mouth, located at the terminal end of the snout.
Regarding the fins, the Electrophorus electricus it is devoid of the pelvics and dorsal muscles. In contrast, the anal fin is long and wavy, with more than 250 rays of soft texture. It extends the entire length of the lower body, up to the tail. Its function is to propel the fish during its movements.
In recent studies, researchers identified remnants of bones corresponding to a true tail. This contradicts the traditional view that this species ancestrally lacked a tail..
As for the vital organs, they are located in the anterior region of the body, occupying about 20% of the total area of the fish. The rest of the body space is occupied by the electrical organs.
The electric eel is characterized by having a highly vascularized respiratory system. In addition, their gills are degenerated, participating mainly in the process of eliminating carbon dioxide..
The absorption of oxygen occurs mainly in the mouth, rich in blood vessels that allow gas exchange. In addition, it is lined with numerous papillae, which expand the surface to carry out the respiratory process.
The Electrophorus electricus you need to breathe air, so you need to get out of the water with some regularity to take in oxygen and then dive back into the depth of the stream.
The researchers maintain that the eel has adaptive behaviors commensurate with the oxygen level of the environment. Thus, when it is low, the animal accelerates the rate of its breaths.
The skin is not covered with scales. The upper body area is usually brown or dark grayish brown. In relation to the ventral area, it has a bright orange or yellow color. However, in the mature female these tones darken.
Electrocytes are flat, elongated cells that make up electrical organs. These are aligned, so that the ion stream flows through them. They are also stacked, allowing each one to add potential to the electrical charge..
Although the charge lasts about 2 or 3 thousandths of a second, it can be repeated up to 150 times every hour, without the eel showing signs of fatigue. When the animal is immobile, it generally has no electrical activity.
However, when it begins to move, it emits small pulses, at a rate of approximately 50 per second. Although the electrical discharge could stun fish twenty feet away, the eel is not harmed.
As in some fish of the superorder Ostariophysi, the swim bladder is divided into two chambers. The anterior is connected to the inner ear, through the Weber apparatus. This is made up of a group of small bones, which are derived from the cervical vertebrae.
Thanks to this particular characteristic, the E. electricus he has an enormous hearing capacity and an excellent sense of hearing. As for the posterior chamber of the swim bladder, it is extended along the entire length of the body, thus allowing the buoyancy of the fish.
The electric eel is the only species among the Gymnotiformes that has three pairs of electric organs: Main's organ, Hunter's organ, and Sach's organ. These are responsible for producing electricity.
The organ of Main is located on the dorsal side of the fish, encompassing the middle half of the body, from the back of the head to the middle of the tail. As for the electric organ of Hunter, it is located parallel to the organ of Main, but towards the ventral side.
Both organs generate high-voltage impulses, which stun prey and deter predators. In the back room of the Electrophorus electricus is the organ of Sach, responsible for producing low voltage pulses.
Thanks to these impulses, the animal can communicate and navigate in the murky waters. In addition, this organic structure constitutes the negative pole of the eel..
The organs have between 5,000 and 6,000 electroplates grouped together, which could generate a discharge of 600 volts up to 1 amp. When the shaker, as this species is also known, is in the juvenile stage, it produces a lower voltage, around 100 volts.
This fish also possesses tuberous receptors, which are sensitive to high frequency. Said structures are distributed over the body in the manner of patches. Experts indicate that its function could be related to the hunting of other Gymnotiformes.
The electric discharge occurs because the nervous system of the electric eel contains electrogenic cells that produce electricity, arranged in the form of disks, called electrocytes..
The periphery of each of these has a net negative electrical charge, with a potential difference of 100 millivolts, with respect to the deeper internal areas of the cell, which are positively charged..
Through active transport, the potassium ions that are located outside the cell cross the membrane and enter the cytoplasm, which causes some of these ions that are inside to leave, with the intention of achieving a balance. This process releases approximately 50 millivolts of electricity..
Because the electrogenic cells are stacked side by side, the millivolts generated trigger a collective discharge, causing the eel to produce up to 600 volts..
The Electrophorus electricus uses electricity for various purposes. The low voltage is used to detect the environment that surrounds it, while with the high voltage it can defend itself, in addition to detecting and stunning its prey..
Also, by snuggling, you can focus the shock on two areas of the body. If the electric eel is agitated, it could release electricity intermittently, for about an hour. However, during that time the fish shows no signs of exhaustion.
In addition, this animal is capable of controlling the nervous and muscular system of its prey, for which it uses the electricity they originate. Thus, it prevents it from escaping.
The electric eel is found in northeastern South America, including the Orinoco river basin, in addition to the lower and middle basin of the Amazon river. Thus, it can be located in Brazil, Colombia, Bolivia, Ecuador, French Guiana, Peru, Guyana, Venezuela and Suriname.
This fish lives in fresh waters, on coastal plains and the muddy bottom of swamps, rivers and streams, from where they must frequently emerge to breathe oxygen.
Young eels often live in groups in sandy areas, where the flow of water is slow. Once they reach maturity, they become lonely.
The E. electricus It is a species of nocturnal habits that prefers stagnant or calm, shallow waters, where it can be found between the roots of aquatic vegetation.
-Animal Kingdom.
-Subkingdom: Bilateria.
-Phylum: Chordate.
-Subfilum: Vertebrate.
-Superclass: Actinopterygii.
-Class: Teleostei.
-Superorder: Ostariophysi.
-Order: Gymnotiformes.
-Suborder: Gymnotoidei.
-Family: Electrophoridae.
-Genus: Electrophorus.
-Species: Electrophorus electricus.
The various South American populations of the electric eel have decreased, for which several organizations (national and international) carry out research on their condition..
The results show that, at present, the communities of Electrophorus electricus they are stable and not fragmented. However, the IUCN lists this species as of least concern to become extinct.
For this categorization, several factors were considered, among which are its great spatial distribution, the great capacity to live in different habitats and the few generalized threats that affect the species..
Among the threats that affect the electric eel is its capture, to be commercialized to aquariums, where they are an important attraction for visitors. Also, in some small Amazonian regions, locals consume meat, making traditional local dishes with it..
The E. electricus is an important source of study, because the scientific community is interested in knowing the details of its electrical capacity and its application in different fields of daily life.
The electric eel is an oviparous animal, whose mating occurs in the dry season. Some specialists point out that it is at the beginning of said season, while others suggest that it is during the course of it..
In investigations carried out in the spawning areas, the experts observed that not all females with developed gonads laid eggs. This could suggest that reproductive success is probably associated with the female finding suitable places to reproduce..
The female lays about 17,000 eggs in a nest, built by the male with his saliva, on the surface of the water or between the roots of some aquatic plants, among which is the Montrichardia arborescens. Spawning occurs in a fractional manner, in three successive batches.
The eggs that have been deposited are fertilized by the male's sperm. The larvae grow until the middle of January. At that time, the first rains flood the breeding area, causing the young eels, which measure around 10 centimeters, to disperse.
The first larvae could feed on the other eggs and embryos from late spawning. The young remain close to the parents, but will soon swim alone.
When the youngsters are approximately 15 millimeters long, the electrical organs are already developed, allowing them to orient themselves. Upon reaching 40 millimeters, they are already capable of generating strong electrical currents.
Generally, electric eels are classified as piscivorous animals, however, they are probably a widespread carnivore.
This is because it tends to feed on shrimp, crabs, fish, tetrapods, small mammals, and aquatic and terrestrial insects. In addition, occasionally you can consume the fruit of the asaí palm tree (Euterpe oleracea).
The diet varies according to the stage of development in which it is. Thus, when the electric eel is in the juvenile phase, it mainly feeds on invertebrate animals. If food became scarce, it could eat the other eels that have not hatched.
Upon reaching adulthood, expand the diet, incorporating fish, birds and small mammals, such as rodents.
To find his prey, the Electrophorus electricus uses the Sachs organ. It transmits a weak pulsating signal, which is also used for directional and location purposes..
When it finds the prey, the electric eel emits a much stronger signal, which stuns the prey. This he does through the organs of Main and Hunter.
If the animal is small, the electric shock could kill it. On the contrary, if it is larger, it does not kill it, but it stuns it enough to be able to capture it. Likewise, this species has the ability to modulate the electrical emission, making controlled discharges against the animal that it wishes to capture..
In this way, the frequency of the shock interferes with the prey's nervous system, stimulating its motor neurons and causing involuntary movements. This causes the prey to move uncontrollably in any direction, preventing it from hiding..
The eating habit of attacking its prey in a surprising way may be the evolutionary product of the animal's need to protect its mouth from the injuries that the fish they catch, who fight for their lives, could leave.
Thus, due to the stunning of the prey, it can be sucked into the eel's mouth and directed to the stomach. Sometimes, depending on the size of the prey, it does not need to impact it with its electric shocks, but rather swallows it quickly.
Experts have shown that Electrophorus electricus it wraps its body around the elusive or larger animals. After this, the eel discharges numerous electric shocks, which fatigue the prey, thus facilitating its consumption..
This strategy has the intention of doubling the strength of the electric field that exists between the positive pole, which is located near the head, and the negative pole, located on the tail..
The electric eel is not an aggressive animal. The strong electrical discharge that it can produce is used by the animal to feed itself and for defensive purposes. In addition, low intensity ones are used for electrolocation and to detect objects..
It is a nocturnal animal, which can hide during the day among aquatic plants or in various types of shelters, such as holes and crevices..
To move in the waters where it lives, this species waves its long anal fin, which extends ventrally on its body.
Occasionally, to deliver strong shocks of electricity, this animal may jump out of the water or put its head briefly above it and touch an animal that is partially submerged. Thus, the electric current enters directly into the body of its prey or the predator that stalks it..
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