We’ve gone to the moon, harnessed the power of the sun, decoded human DNA, and even learned about the lives of creatures that walked the earth long before us. But there’s one peculiar mystery scientists just can’t seem to figure out: freshwater eels. More specifically, how do they create new ones?

From Aristotle to Sigmund Freud, many of the greatest minds of recorded history have pondered the reproductive habits of—of all things—eels. Why should we care about how eels reproduce? Well, it’s a mystery that points to a fundamental truth about our planet and, well, us: we don’t know everything!

Freshwater eels travel enormous distances, live in habitats that span the Bermuda Triangle to the rivers of Europe, and they have extraordinarily complex lives. If an eel can be this complicated, it’s an important reminder that we still only understand a tiny fraction of our planet’s extraordinary complexity!

Let’s discover why an eel poses one of the greatest unsolved mysteries on our planet!

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Are they born from dandruff? What about from raindrops? Maybe they just eject from the mud? Or other fish? Where do these eels come from?!

Yeah, that’s right. We know how birds do it, how snails do it, and even how seahorses do it, too, but as much as we think we know about the world, we still have no idea how these eels have sex and reproduce!

These eels have quite the life. Yet, even today, no one knows how it begins. It took centuries to figure out where their reproductive organs were, and still, the question of where freshwater eels go to do the deed and how they do it continues to elude us.

Part of the story as to why this is so puzzling has to do with the number of life stages and appearance changes these river eels go through, even before they make it to the river.

At one point, they’re even see-through! This variation in looks didn’t make it easy for scientists to track one species of eel through its life span… since they thought they were different ones all along.

To catch us up on the whole fascinating story and find out where we’re at in uncovering this great wonder of the world, here’s TED-Ed!

Via: TED-Ed 1

TED-Ed is one of our all-time favorite creators here at EWC! Every single one of their videos introduces us to fascinating concepts about the world in the most unique ways. Check out their full library by clicking here!

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How wild was that?!

We’ve been able to learn so much about the world and yet we are still puzzling over the mysteries of the freshwater eel!

I know you’re itching to learn more, so I’ve got something that will delight your ears with eel facts. In this awesome episode of Radiolab, biologist Lucy Cooke—whose enlightening and inspiring TED Talk on sloths is one of our favorites—gives us more of the dirty details about the race to find the origins of our slippery friends.

(Click on “Listen For Free” to go to their site.)

Via: Radiolab 2

If you’re sitting there right now like, “Wow, I wonder what else this scientist knows!?” then, my goodness, are you in luck. In addition to her book, we’ve published two other articles that feature her awesomeness. Check these out if you’re wanting to discover more about the wacky world of creatures we live in!

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Life Advice from the Slowest Mammal on Earth!

What can sloths teach us about dealing with the chaos of modern life? Here's a hilarious TED Talk that will have you becoming a champion of the sloth lifestyle for yourself.

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Artificial Intelligence Meets Black Soldier Flies and Farming!

When it comes to saving the resources of our planet, we are all hoping for the next big idea to come along. Well, this one involves a very tiny creature that brings an amazing resume to the task. Let's meet them!

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Fueled by wonder!

You may be wondering what good it does for us to learn how eels reproduce.

How does knowing—or more accurately, knowing that we don’t know—prove that it’s still an amazing world?

I ask you to sit on that for a moment. Because isn’t it the unknown that has always pushed us forward? If camera phones, CAT scans, and baby formula all came from a desire to explore space 3, what innovations could come from us finding ways to track the eels to where they begin? In our pursuit of this simple curiosity that has haunted scientists for centuries, what will we discover along the way?

The payoffs of pursuing our wonder aren’t always obvious.

Maybe the next great innovation will come from exploring this great mystery, or maybe it won’t. The thing is, as my friend, marine biologist Nathan Robinson said so perfectly in this article about giant squids, “the more that we learn about something, the more beautiful they become.”

Stay open to new possibilities!

  • Sam

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If you’d like less fear, more joy and a direct path to a brighter future, here’s how to connect with a world full of possibilities that no one is talking about. Choose your medium:

And most of all, SHARE THE GOODNESS. The more we spread goodness, the more impact we can have, together.


  1. TED-Ed. “No One Can Figure out How Eels Have Sex – Lucy Cooke.” YouTube, 27 July 2020, www.youtube.com/watch?v=RFi6ISTjkR4. Accessed 11 Aug. 2020.
  2. “Silky Love | Radiolab | WNYC Studios.” WNYC Studios, 2019, www.wnycstudios.org/podcasts/radiolab/articles/silky-love. Accessed 11 Aug. 2020.
  3. JPL.NASA.GOV. “JPL | 20 Inventions We Wouldn’t Have Without Space Travel.” JPL Infographics, 2017, www.jpl.nasa.gov/infographics/infographic.view.php?id=11358. Accessed 11 Aug. 2020.

Sam has written and edited hundreds of articles since joining the EWC team in 2016. She writes about topics from the wonders of nature to the organizations changing the world and the simple joys in life! Outside of the EWC office, she’s a part-time printmaker, collector of knick-knacks, and taster of cheeses.