Where do eels come from?
Every now and then we across an article which makes us realise just how little we understand of the world around us. This piece from the New Yorker not only highlights the limits of our knowledge but also how that lack of knowledge isn’t preventing us from wrecking the world which we live in. This article delves into the fact that no one has ever figured out where eels come from. We don’t know how they mate and no one has ever identified any sexual organs in their body.
A host of great minds have tried to resolve this mystery: “The young man, whose name was Sigmund Freud, eventually followed his evolving questions in other directions. But in Trieste, elbow-deep in slime (in 1876), he hoped to be the first person to find what men of science had been seeking for thousands of years: the testicles of an eel. To see them would be to begin to solve a profound mystery, one that had stumped Aristotle and countless successors throughout the history of natural science: Where do eels come from?
The nineteenth century had brought Darwin and Mendel, Pasteur and Mendeleev, and a growing sense that scientists (a word coined only in the eighteen-thirties), with their studies and their systems and their microscopes, were at last equal to solving the great quandaries of the natural world. Questions that had befuddled mankind for centuries—where life comes from, what it is made of, how it changes, why it ends—were now seen as knowable, quantifiable, explicable. Just two years before Freud arrived in Trieste, the German biologist Max Schultze, lying on his deathbed, observed, perhaps wistfully, that he was leaving a world where “all the important questions . . . had now been settled.” All of them, that is, “except the eel question.””
Until 40-50 years, eels were a commonly consumed food across European countries with each country having its distinctive way of preparing what was then a commonly available fish: “People caught eels in brooks, rivers, lakes, the sea. They also caught them, inexplicably, in ponds that dried out and refilled each year, and that had no access to other bodies of water. They couldn’t help but notice that the creatures seemed to have no ovaries, no testicles, no eggs, no milt. That they were never observed to mate. That they sometimes seemed to issue from the earth itself.”
Gradually, observers uncovered some of the mysteries around this remarkable creature: “The truth emerged only slowly, and was, in its own slippery way, stranger than the fiction. Careful observers discovered that what had long been taken for several different kinds of animals were in fact just one. The eel was a creature of metamorphosis, transforming itself over the course of its life into four distinct beings: a tiny gossamer larva with huge eyes, floating toward Europe in the open sea; a shimmering glass eel, known as an elver, a few inches in length with visible insides, making its way along coasts and up rivers; a yellow-brown eel, the kind you might catch in ponds, which can move across dry land, hibernate in mud until you’ve forgotten it was ever there, and live quietly for half a century in a single place; and, finally, the silver eel, a long, powerful muscle that ripples its way back to sea. When this last metamorphosis happens, the eel’s stomach dissolves—it will travel thousands of miles on its fat reserves alone—and its reproductive organs develop for the first time. In the eels of Europe, no one could find those organs because they did not yet exist.”
Then in 1904 Danish research Johannes Schmidt took it upon himself to figure out where exactly in the Atlantic Ocean the eels came from. After 20 years of painstaking search he reached an answer: “Schmidt had traced the Anguilla Anguilla (the biological name of the eel) to the Sargasso Sea—a sea within a sea, a garden of seaweed bounded not by land but by great currents of water. (The American eel breeds there as well, and it is still something of a mystery how the larvae, all mixed together but genetically distinct, know which continent is their future home.)”
Even this knowledge nobody could figure out where eels came from or how they were created: “Many expeditions have followed Schmidt to the breeding grounds in the decades since, each with better technology than the last. They, too, have found plenty of larvae, but, when one expedition collected and examined seven thousand fish eggs, not one of them turned out to be from an eel. Scientists have put G.P.S. trackers on silver eels beginning their migration; they’ve used hormones to bring females into heat, transported them to the breeding grounds, and attached them to buoys to use their pheromones as bait. They have dropped microphones into the water and opened the stomachs of predators. And yet no one has ever seen Anguilla anguilla mating anywhere, or so much as set eyes on a mature eel, living or dead, in the Sargasso Sea.”
You might ask why should you and I care about trivia such as this. The answer: “The formerly ordinary, everyday eel is classified as critically endangered, the last official designation on the road toward nonexistence. (Well, there is also “extinct in the wild,” but without their wild breeding grounds eels are nothing. No one has ever managed to breed them in captivity.) Svensson writes, “This is the latest and most urgent eel question: Why is it disappearing?””