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Thanks to Cosmo for suggesting this week’s animal, the electric catfish!
Further reading:
The shocking truth about electric fish
Efficient high-voltage protection in the electric catfish
Gimme kiss [electric catfish photo from this site]:
Show transcript:
Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.
This week we’re finally going to talk about a fish Cosmo wanted us to learn about, the electric catfish!
Catfish are really common fish that live throughout the world, except for Antarctica. We’ve talked about various types of catfish in lots of different episodes, since there are well over 3,000 known species and they’re incredibly diverse. The electric catfish lives in freshwater in tropical areas in western and central Africa, as far north as the Nile River.
All animals generate electric fields in their nerves and the contracting of muscles. Animals that can sense these fields are called electroreceptive. An electroreceptive animal can find hidden prey without using its other senses.
Many electroreceptive animals can also generate weak electrical fields, usually less than a single volt—small electrical pulses or a sort of wave, depending on the species, that can give them information about their environment. Like a dolphin using echolocation, a fish using electro-location can sense where potential prey is, where predators, plants, and rocks are, and can even communicate with other fish of its same species. Of course, those same electric pulses can also attract electroreceptive predators.
Some fish can generate an electric shock so strong it can stun or kill other animals. The most famous is the electric eel, which we talked about way back in episode 10, but the electric catfish falls in this category too.
The electric catfish isn’t a single species but several in the family Malapteruridae. Some are very small, but one grows as much as four feet long, or 1.2 meters, and can weigh over 50 lbs, or 23 kg. That’s Malapterurus electricus, THE electric catfish.
The electric catfish is grayish-brown mottled with black spots. Like a lot of catfish, it’s a cylinder-shaped chonk, and has three pairs of barbels around its broad mouth. Barbels are the feelers that give the catfish its name, because they look sort of like a cat’s whiskers. Sort of. Not actually very much like a cat’s whiskers. The electric catfish also has what look like surprisingly kissy lips, which are often pale in color so they stand out, especially when the mouth is open, which is frankly hilarious. It doesn’t have a dorsal fin and it’s not a fast swimmer. It spends most of its time lurking in rocky areas in muddy, slow-moving water. It’s also nocturnal.
The electric catfish eats other fish, although it will also eat pretty much anything it can swallow. It likes muddy water because it doesn’t want potential prey to see it, and of course it doesn’t want any potential predators to see it either. That includes humans, who consider it a delicacy. Humans also sometimes keep electric catfish as aquarium fish, which is sort of the opposite of being killed and eaten.
Contracting a muscle causes a tiny, tiny electrical impulse, as I mentioned earlier, but in electric fish certain muscles have developed the ability to generate much stronger electrical impulses. Instead of muscles, they’re called electric organs. The interesting thing is that this is only found in fish, but that the ability evolved separately at least six times in different lineages of fish.
The electric catfish uses its ability to generate electric shocks as a defense when it needs to, but mainly it uses it to stun or outright kill other fish, which it then gulps down. It can discharge up to 300 volts of electricity in pulses that last only a few milliseconds, but since it can generate up to 500 pulses in waves, that’s a lot of electricity. That’s not enough to kill a person, but you’d definitely feel it and try to get away.
But, you may ask, how does the electric catfish not shock itself? Water is a really good conductor of electricity, which is one reason why this ability is only found in fish. A study published in 2022 asked that question too. The scientists used a high speed digital camera to observe captive electric catfish, and got them to discharge electricity by tickling them with a paintbrush. This allowed the scientists to see if the catfish was actually affected by its electricity at all, because the main outward sign of electrocution is involuntary muscle contractions. They determined that no, the catfish didn’t show any sign of being shocked. They also weren’t shocked when the scientists were the ones generating electricity in the tank. The conclusion is that the electric catfish is shielded by a layer of fat and other tissues that resist electric shocks, which are especially dense around the animal’s heart and nervous system.
Arthritis in humans is sometimes alleviated by the application of mild electric shocks, carefully administered by doctors, but in ancient times before electricity, people figured out that handling some fish helped arthritis. Since electric fish are pretty common in different parts of the world, different cultures figured this out at different times. The ancient Greeks would put an electric ray on the arthritic body part, for instance, while the ancient Egyptians used the electric catfish. The ancient Egyptians depicted the electric catfish in carvings and paintings that are over 5,000 years old. I have arthritis in my thumbs but I don’t think I want to touch an electric catfish with my thumbs.
You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.
Thanks for listening!