Despite many theories and ideas surrounding the mystery, the truth is eels come from external reproduction. That is to say, they release eggs and sperm into ‘clouds’.
Eels have baffled scientists and storytellers alike for centuries. Unlike many other animals, they don’t lay eggs in rivers or lakes. In fact, for years, no one had ever seen an eel reproduce!
Many claims across the internet describe the mystery of eel reproduction and how we ‘have no idea where eels come from’. They even go as far as to say we’ve never seen eels reproduce in the wild nor in captivity.
Fresh eels in Vietnamese market, Mui Ne.
As captivating and mystical as this idea sounds, it’s simply false. We have in fact seen eels reproduce in captivity and we’re pretty certain about the external reproduction theory.
Where do the theories come from?
You may be wondering, and rightly so, why on earth anyone would make something like this up. The honest answer may be, they didn’t realise it wasn’t true.
The truth of the matter is that eel reproduction, while it does happen, isn’t as common as it ideally should be. The European eel, for instance, is critically endangered with only 20,000 left in the wild.
Despite this, eels seem in no rush to save their species as those that find themselves in captivity reportedly don’t reproduce at as fast a rate as their capable of. As stated above, they release eggs and sperm in ‘clouds’ which mix and fertilise one another, eventually resulting in brand new eels.
The common myth surrounding eels not having any reproductive organs is also not true. Scientists that have dissected eels have never made such claims; in fact they’ve said the opposite. Reproductive systems can be found in eels of a certain age.
Another probable reason for the popularity of this hoax is that their method of reproduction is different to humans. In order to avoid a talk about the birds and the eels, I’ll keep it to this; we definitely do not release clouds of eggs and sperm.
Not Snakes, Not Fish — Something In-Between?
Eels look a bit like snakes, but they’re actually fish! They have long, flexible bodies and can wriggle through the smallest gaps. When young eels (called glass eels because of their see-through bodies) arrive at our coastlines, they swim up rivers and transform into elvers, and eventually, into the adult eels we might spot in ponds or streams. Some even live for more than 50 years before making the journey back to the Sargasso Sea to lay their eggs and die. No one has ever seen this return journey happen in the wild — it’s one of nature’s greatest secrets!
Why Eels Matter — and Why They’re Disappearing
Sadly, the number of eels in the UK has dropped by over 90% in the past few decades. Pollution, dams, and illegal fishing all play a part. Yet eels are vital for our ecosystems. They eat dead animals, keep river life in balance, and provide food for birds and larger fish. Protecting them means protecting rivers for all wildlife — and for future generations of curious children wondering where these wiggly, weird creatures come from.
A Journey Without a Map
One of the most incredible things about eels is that they seem to navigate thousands of miles without any help or guidance. From tiny glass eels drifting across the Atlantic to grown adults making their mysterious return to the Sargasso Sea, no one fully understands how they find their way. Scientists think they may use the Earth’s magnetic field to travel — a bit like having an internal compass! It’s a skill no human has mastered without a GPS, but the eel has been doing it for millions of years.
The Ghost Eel Stage
When eels first arrive at European shores, they are almost invisible. These tiny creatures are known as glass eels because their bodies are completely transparent. It’s only after they move into freshwater rivers and lakes that they begin to gain colour, becoming the darker, slippery eels, we might recognise. This “ghost stage” helps protect them from predators during the most dangerous part of their migration — it’s like nature’s own version of invisibility!
A Puzzle for the Ages
Even the great thinkers of the past couldn’t crack the eel’s life cycle. Aristotle thought eels were born from mud. Sigmund Freud, before becoming the father of psychology, spent part of his youth dissecting eels in search of reproductive organs — and found nothing! That’s because eels don’t develop their reproductive organs until just before their final journey back to the Sargasso Sea. Until then, they keep their secrets well hidden.
Which other animals reproduce differently?
Ignoring the obvious examples such as intercourse, laying eggs etc, what other ways do animals reproduce?
An interesting quirk of the Argonaut, the only cephalopod that creates and lives in a shell, is a certain detachable appendage, As females are much larger than males, reproduction becomes a dilemma. To get around this, male argonauts are able to detach and ‘fire’ a modified arm filled with reproductive cells towards a female. This enables them to reproduce without worrying about the size difference. Incredible!
The antechinus is a small mouse like marsupial that mates continuously until it dies. Literally. Males, upon reaching 11 months old, have produced all the sperm they ever will. Then, for the next 2 weeks, they mate with any and every female they can find (sometimes for up to 14 hours each) one after another until their bodies break down.
An interesting case of reproduction involves seahorses. These little aquatic equines are one of the only species on earth in which the MALES get pregnant and give birth. A completely, remarkably rare trait that has no advantage or disadvantage, simply an interesting quirk. Facts like these make me love researching animals more and more.
Overall, we can see that eel reproduction isn’t all that special and, in actuality, the most interesting part is the mysterious and conspiracy-inspiring nature of it.
Extra Information
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