What if I told you that we, as humans still have no idea how eels reproduce? That’s right. You read it correctly. We have been to the moon, searching for new planets that support life at this very moment, but we still have not figured out how eels reproduce. Because eels do not have sex organs.
Even though these unusual fishes have been present for almost 40 million years and have made enormous contributions to human history, culture, food, and mythology, major aspects of their life cycle and reproductive activities are unexplained.
Aristotle the great philosopher thought that eels do not develop reproductive organs because they don’t reproduce. And since they don’t reproduce, he thought that they must come to life through some other means and concluded that eels spontaneously emerge from the mud when mixed with rainwater.
In his laboratory on the island of Lesbos in the fourth century BC, Aristotle cut open numerous eels in pursuit of evidence of genitalia. He discovered no sex organs in any of the eels he examined, leading to his controversial idea of spontaneous generation, the hypothetical process by which living organisms develop from nonliving matter.
Although incorrect, we can see that he was one of the first to try and tackle this mystery.
Sigmund Freud, an Austrian neurologist went so far as to spend 10 hours a day dissecting eels in an effort to find something that pointed to the reproductive organs. He would go to the local pier every day and buy all of the eels that were available. He spent so much time with the nasty creatures that he began to start to hallucinating and seeing them everywhere. It was said that Sigmund Freud dissected 400 eels looking for testicles.
What little we do know about these eels is that they live in freshwater rivers but when they become old, they move to the Bermuda Triangle and then new eels come back. Yes, Bermuda Triangle. So many conspiracy theorists have gathered around this fact, believing that eels are the work of aliens, demons, or even government devices. Crazy right?
Eels being able to move from freshwater to saltwater and back is a mystery on its own. This is because if you take a freshwater fish and toss it onto the ocean, it is most probably going to die. Furthermore, eels go through a lot of metamorphic changes throughout their life. Eels have 5 stages of life. Up until recently, it was believed that each life stage of eels was a completely different species. Given the radical physical differences between these phases, you’d be forgiven for assuming these are different animals. However, now we’ve identified they are the same animal. (Larval Leptocephali, Glass Eels, Elvers, Yellow Eels, and Silver Eels)
An eel can live for up to 85 years. Researchers have found that Eels begin their lives as tiny eggs, the size of a grain of rice. But how these eggs are produced remains a mystery. The Sargasso Sea, the deepest, saltiest portion of the Atlantic Ocean which is right in the midst of the Bermuda Triangle and is believed to hold these tiny eggs suspended in the depths of an underwater forest. They go through two complete metamorphoses and travel roughly 4,000 miles to the rivers of North America and Europe during the next 3 to 7 years. Then they creep upstream and bury themselves into the substrate, devouring everything they can find. Then these fish return to Sargasso somewhere between 7 and 30 years later, experiencing the remaining metamorphoses.
Eels are strange creatures. That’s about all anyone can say about them with certainty. From Aristotle to Freud, these slithery fish have puzzled history’s greatest brains. We may be able to save these fish if we gain a better understanding of them. We don’t know how many offspring each eel can produce or what percentage of them survive the massive migration and therefore we don’t know how near they are to extinction. If we don’t figure out this millennia-old mystery soon, we may never get the chance.