More than a century ago, all that people knew about European eels was that they lived in the rivers and streams for decades — until they swam out to the ocean and never returned. Eventually, tiny eels would show up and the cycle would start again. Where did the adult eels go? Where did the baby eels come from? Did they even reproduce at all or just spontaneously emerge into being? Science now has some — but not all — of the answers to these questions. Today on the show, Regina G. Barber talks to fish physiologist Arjan Palstra about this mystery and how close scientists are to solving it. 

If you liked this episode, check out our episode on the Pacific lamprey.

Interested in more science mysteries? Email us your question at [email protected].

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