Science Facts

How Do Eels Generate Electricity? – Causes & Explanation

Eels Electricity

Electric eels have fascinated scientists and the public for hundreds of years. Even Charles Darwin was puzzled by them. What is the shocking secret behind an electric eel’s weapon? An eel uses an electric shock of 650 volts to kill its prey. Believe it, or not all living animals produce an electric charge during everyday muscular movement, but it’s very little. A nerve impulse is an electrical signal running through the length of a nerve reaching speeds of over 200 miles per hour. By sending an electrical pulse through the nerves via contraption, muscles should contract and try.

Electric eels are some of the most shocking organisms on this planet. They can harness the power of electricity to hunt. But electric eels aren’t eels at all. They’re a type of knife fish found in the Amazon River Basin in South America. They’re just one type of dozens of fish that use electrical fields as a sort of extrasensory perception. But they’re the only ones with a charge strong enough to kill. Basically, electric eels and other fish have modified muscle cells that stack on top of each other. They work kind of like batteries.

How do eels generate electricity?

Electric Eels are one of nature’s best. They can make electricity up to 500-600 volts, way more than the average Socket. At a length of more than 2 meters, they are taller than most humans. Despite their name, they are not eels, but they fall in a category of fish called knife fish. There is a fascinating way how eels manage to generate electricity strong enough to knock down a horse.

Electric fishes are primarily found in freshwater rivers of Africa and South America, including the Amazon rainforest. They are divided into two categories:

  • Strong electric fish.
  • Weak electric fish.

Strong electric eels can produce very high voltages, whereas weak electric fish currents are too weak to stun their prey, so they use it for navigation or communication. Eels have three main organs to help them. The electric organ and hunter’s organ are used for high voltage electricity used for stunning the prey. They have thousands of cells called electrocytes in the electric organ, which are stacked up together.

Water and electricity make the perfect match. Water is such a good conductor. Each time a fish contracts a muscle. And it sends extremely weak electrical signal pulses through the water. So it’s not surprising that predatory creatures like the hammerhead shark can detect these electrical signals like a sixth sense. It allows them to find prey even when it’s out of sight, hidden beneath the sand. Many fish have taken this to the next level and can produce super-strength electrical charges.

Electric eels have a series of electricity-generating cells which pulse and create an electric field around them. If anything comes into this field, it bounces back a signal to the eel. That allows it to build up a map of its surroundings. So it can see even in muddy water! And amazingly, to electric fish come together, they will change the individual frequency, so they don’t journal each other’s output.

Electricity generation system

The electric eel can generate its own massive electrical pulse dystonic spray. Each electricity-producing cell generates just 130 millivolts. So the fish stack them up in series. It’s a bit like putting a group of batteries pinned on ends inside a torch to increase the voltage.

Typically an eel can have as many as 6,000 electrocytes. As many as 6000 such cells in series, the fish can generate 650 volts delivered at approximately one-half. That’s about the same as a domestic microwave. These stacks of cells are negatively charged inside, and their outsides are positively charged.

Each cell has the potential of .08 volts. Not a lot, and considering the charges alternate, no current flows. But as soon as the eel is triggered by spotting a potential prey, these cells open up, and an influx of sodium ions changes the polarity. The stacks have a positive and negative end which creates an electric current.

Chemical reaction: When an atom loses or gains electrons, it gathers either a positive or negative charge. An electron has a negative charge, so losing it will result in an overall positive charge for the atom. That’s the main power eels use. In the electrocytes, sodium and potassium ions are positively charged and pumped out of the cell constantly. So there is a positive charge outside and a negative charge inside.

NaCl(s) → Na+ (aq) + Cl−(aq)

But, the charge is reversed when the eel uses its ability or ‘fires’ using neurotransmitter acetylcholine and pacemaker neurons. It doesn’t pump all the charges outside and allows ions to flow back in. So, one side has a positive charge inside while the other has a negative charge on the other side. Thousands of such cells stacked up together have this same pattern.

As electricity moves from positive to negative terminals, the eel produces massive shocks, acting as a battery. It is known as an Electric Organ Discharge(EOD). There are two types of EOD’s pulse type and wave type. Pulse-type fish send electric fields at irregular intervals, whereas some weakly electric fishes send continuous wave-like electricity.

Why do electric eels generate electricity?

Their shocks have a stealth mode. They have a low-voltage version that helps them hunt. These electric shocks act an awful lot as sonar bats use. They can send them out as feelers, sensing if any fish are lurking nearby. But even their big shocks have a dual function. One study published in the journal Nature Communications found it’s for hunting too.

The lead author of the study told National Geographic that “The eel can use its electric attack simultaneously as a weapon and a sensory system, it’s sort of a science-fiction-like ability.” Once they hone in on prey, they have a “remote control” mode. They send out two closely spaced high-voltage discharges called doublets, making the prey’s body contract involuntarily. This movement sends ripples through the water. It lets the eel know it’s an alive thing and possibly prey. It can even make the fish “freeze.” It shocks their neurological system, so the fish can’t move.

While ideal for catching smaller prey, sometimes the shock isn’t enough for catching larger fish. So an eel has to amp up its power. A recent study published in the journal Current Biology found that eels boost their electric zap by curling into a circle. It brings the positively charged end of their body, head, and negatively charged tail area.

By bringing the two points closer together, the fish can double their shock. While their shock isn’t enough to kill a person, it’s still pretty painful. Those who’ve experienced it say it’s a lot like running into an electric fence.

Why doesn’t eel itself get electrocuted?

There are various understandings on this question. They may have particular proteins to protect them or twirl their bodies in such a shape that prevents electricity from reaching their heart. But the truth is, we still haven’t figured that out completely. Eels send out high voltage pulses, which twitch the prey’s muscles involuntarily.

The electric organ is at the base of their tail, far away from the heart, brain, and other vital organs situated much nearer the head than in others fish. As water is more conductive than body tissue, the charge travels away from the fish. It’s also thought that many of the vital organs are covered in a layer of fat, insulating them against the dangerous electric charges. It is because the supercharged electric blast is delivered just a tiny stone prey. The current probably doesn’t last long enough to shock a giant 2-meter electric eel.

One scientist, Kenneth Catania, has researched electric eels hunting their prey, and he has found some fantastic results in his research. In one of his experiments, he infected the fish with curare, a poison that blocks the junctions connecting nerves and muscles. And when he brought the eel near it, he found that no change happened to the fish. It didn’t die, nor were its muscles paralyzed. That means the eel directly attacks the nervous system instead of the muscles.

This was a fantastic outcome. It does not attack the muscles but directly blocks the nervous system connecting the muscles. Electrolocation is also a fascinating aspect of strong and weakly electric fish. The Elephantnose for example, uses electric organ discharges to locate objects. First, it sends out these signals using the electric organ. If an object is in contact or a slight change in the field, the fish uses sensors called electroreceptors buried in the skin to detect the object. This process is called ‘active electrolocation’ because the source of electricity is its own electric organ.

Some fishes cannot generate electricity but can sense it. These animals use ‘passive electrolocation.’ For example, sharks can sense their prey by sensing the electric fields send by them!

More Articles:


David; Crampton, William G. R.; “Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator.” Nature Communications.
Oliveira, Marcos S. B.; Mendes‐Júnior, Raimundo N. G.; “Diet composition of the electric eel Electrophorus voltai (Pisces: Gymnotidae) in the Brazilian Amazon region.” Journal of Fish Biology.

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