In a painful experiment, a US researcher found out just how strong the jolts delivered by the fish are. He had previously found that electric eels have a special technique that makes their shocks extra-efficient.
Image: imago/Olaf Wagner
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Now that's dedication to science: researcher Kenneth Catania tested how strong the jolts are that electic eels use to shock their victims – on himself. Catania, a biology professor at Vanderbilt University in Nashville, in the US state of Tennessee, wanted to understand the dynamics of the circuit created in an electric eel attack. For this, he developed an apparatus that can measure the strength of the electric current through a human arm that gets touched by an electric eel. The experience, Catania wrote in the journal Current Biology, is quite painful.
In his study published on Thursday, the researcher reports that electricity peaked at 40 to 50 milliamps. That's stronger than the jolts delivered by a regular taser and enough to cause an adult human or a large animal significant pain, but not enough to leave long-term injuries. In the wild, the damage could be larger, however – for obvious reasons, Catania picked a small electric eel for his experiment.
"It's impressive that a little eel could deliver that much electricity," Catania said. "We don't know the main drive of the behavior, but they need to deter predators, and I can tell you it's really good at that. I can't imagine an animal that had received this [jolt] sticking around."
Despite their name, electric eels are not in fact eels, but rather belong to the South American knifefish. Almost their entire bodies are covered with electricity-generating organs, so-called electroplaques.
Battle between electric eels and horses
In a previous experiment, Catania, who has been researching electric eels for years, found that the fish leapt out of the water and were thus able to deliver electricity directly from their chins to the victim. Their jolts are more effective this way because no electrical discharge dissipates through the water.
This behavior had been described by Alexander von Humboldt all the way back in the 1800s. The explorer described a dramatic battle between electric eels and horses in the Amazon.
But, Catania said, "No one really… believed it, or if they did, they thought it was just kind of weird."
You can't see them, but this platybus bill is covered in tens of thousands electric sensorsImage: picture alliance/Anka Agency International/G. Lacz
The electric eel is not the only high-voltage animal. The platypus catches its prey in murky water with its eyes closed by honing in on the electrical impulses emitted by their prey. Their bills are covered in almost 40,000 electricity sensors.
Electric rays can produce up to 220 volts. Some of them, like the Pacific electric ray, use this electricity to stun their prey.
The Oriental hornet is a solar-powered insect: its brown stripes trap the sunlight and its yellow stripes convert it into electricity. Researchers aren't sure what the hornet uses this electricity for, but believe that it could help the animals create enzymes that aid in their metabolism.
A close look at marine marvels
The ocean is truly home to some of the most amazing creatures, such as species recently discovered under Antarctica. Here's a selection of the world's most interesting aquatic animals.
Image: British Antarctic Survey/dpa/picture alliance
Unknown life
Under permanent ice cover that is hundreds of meters thick in Antarctica, researchers have discovered sessile animals (similar to sponges) that have adapted to extreme conditions like darkness and subzero temperatures, as well as being under such expanses of ice that these organisms are 260 kilometers (155 miles) from the open sea. To what species the rock-bound creatures belong remains unclear.
Image: British Antarctic Survey/dpa/picture alliance
Water dragon
It looks like a seahorse — but it's a red sea dragon, a rare marine fish. Researchers off the coast of Western Australia have only recently been able to admire these live specimens, which were identified in 2015. The animals were observed feeding at a depth of 50 meters (165 feet).
Image: picture-alliance/dpa/Scripps Oceanography/UC San Diego
Seahorses
The "real" seahorses are also quite unusual. They are one of the few species to swim vertically. But this doesn't work out too well, so they are just poor swimmers. The males carry fertilized eggs and give birth to their young.
Image: picture-alliance/ dpa
Electric eels
Despite its name, an electric eel is not an eel but a knife fish. It is indeed electric, though, and generates powerful electric shocks of up to 600 volts to kill prey. Researchers have learned that the fish also uses its high-voltage discharge as a high-precision tracking device — similar to the echolocation calls of bats.
Image: imago/Olaf Wagner
Banded archerfish
Banded archerfish live in brackish water and have come up with a unique way to kill prey: They spit a jet of water into the air to shoot down insects. Larger fish may even hit targets up to 3 meters away.
This fish buries itself in the sand and waits till its prey passes its head. Then it shoots upward and gets its meal. Stargazers have top-mounted eyes and a large, upward-facing mouth. If you ever see one, be careful: The species is venomous.
Image: picture-alliance / OKAPIA KG
Stonefish
Venomous and good at hiding? The stonefish is both! The species looks exactly like a stone overgrown with algae. But step on it and you will come to know its needlelike venomous spines. It can even be fatal for humans.
Image: gemeinfrei
Puffer fish
Puffer fish have an elastic stomach that they can fill with water when feeling threatened. This way they become much larger and almost spherical in shape. They produce the tetrodotoxin, which can kill humans. In Japan, people eat puffer fish.
Image: picture alliance/Arco Images
Anglerfish
An anglerfish attracts its prey with an illicium, or a fleshy growth from its head. The tip of the illicium illuminates to make prey curious — and then they are swallowed up by the huge mouth of the predator. Anglerfish can be found almost anywhere in the world, including the deep sea.
Image: Flickr/Stephen Childs
Viperfish
With high pressure, almost no light and little food, animals have to be especially adapted to be able to live in the deep sea. Viperfish need to make absolutely sure that they don't miss a meal — that's what the huge mouth and the sharp teeth are for.
Image: picture-alliance/dpa
Plaice
The plaice is a flatfish — no doubt about that. The well-camouflaged fish bury themselves in the sediment. They develop so that both eyes end up on the same side of the head.
Image: picture-alliance/dpa/H.Bäsemann
Mudskippers
Mudskippers apparently couldn't decide whether they liked land or water more. So they compromised and chose intertidal habitats. They are definitely fish but can use their pectoral fins to walk on land. They can breathe through their skin like amphibians.
Image: picture-alliance/dpa/MAXPPP
Hammerhead shark
Researchers believe that the flat, sideways extended head gives hammerhead sharks a higher visual field. That helps them find their prey.
