How Do Eels Reproduce?

breeding lives are still shrouded in mystery. And to get these skinny on eel reproduction for the articles, episode is based on how Stuff Works. Spoke with an expert, Caroline Derriff, an ecologist at the Norwegian Institute of Marine Research who studies the habits of these incredible fish. Okay, first off, calling something an eel doesn't make it one necessarily, no doubt you've heard of the South American electric eel. Despite

common name, that dramatic fish isn't really an eel. It's a Bizarro carp relative that's classified as a knife fish. The order Anguilliforms contains all of the world's true eels. There are more than eight hundred species from Mora's you know, Ursula's sidekicks from the little Mermaid to the aptly named spaghetti. Eels usually slender and elongated a true eels do not have pelvic fins, which are twin appendages often found on

the underbellies of other fish. Eels can be scaleless, Many species feel slippery to the touch, and salt water is the preferred habitat for the majority of eels. However, there are nineteen species of so called freshwater eels or anglid, which spend some stages of their lives in fresh water. They spawn in the ocean, that is, the adults produce eggs and sperm, and then the resulting babies hatched there, but they grow in freshwater before turning to the sea.

Saying that these fish have a complex life cycle is a little bit of an understatement. If it survives to reach sexual maturity, a freshwater eel will have gone through five distinct stages. With each new phase, the animal experiences both a physical transformation and shift in lifestyle. Derec explained. The first stage is called the leptocephalus larva. They're called

leptocephalus because lepta means leaf and cephalis means head. True to the name, the newborn larva have leaf shaped bodies that appear broad and flattened in profile in biological jargon. Their bodies are laterally compressed, being nearly transparent. They're also very well camouflaged. Imagine trying to recover a lost contact lens from the bottom of a swimming pool. Leptocephalus larva

are ocean going animals. Eventually, though instinct pushes them defined change in scenery, which is where the change into the second phase of the life cycle occurs. Derriff said, they migrate for great distances. They drift through the gulf stream, and then when they reach the continental shelf, they metamorphos

into glass eels. A glass eels are still more or less transparent, but they're longer and skinnier by comparison, and they're attracted to fresh water, so they head inland by traveling up rivers, and that brings us to life stage number three, a yellow eels. Unlike the transparent larva and glass eels, these guys have body pigment with a yellowish overall complexion. But it's not the last color change that

the fish will go through. A Derff said, oh, when they're ready, they become silver eels, which is like puberty. We often call them silver because they have a silver belly and a black dorsal area. It's an adaptation to predation. Many fish have the space of color pattern. When from below, their silver bellies blend in with the brighter light coming from the surface, and when viewed from above, their darker backs blend in with the dimmer water below. But this

change in eels doesn't happen overnight. Transitioning from a yellow eel to a silver eel can take twenty or thirty years. Once the process finally ends, they return to their roots and head seaward. Only then can the eels attain sexual maturity, the fifth and final stage in their life cycle. However, we don't know much about the reproductive stage of angle at eels because no one has ever caught a sexually mature eel alive in the wild. Likewise, no one has

observed these eels spawning in their natural habitat. The scientists have yet to catch wild angleids in the act, if you will, whatever happens out there. Experts think freshwater eels die shortly after mating. The laboratory researchers have managed to sexual maturity in silver eels by injecting them with hormones. But after the transition their health declines, and Dereff said

the bones become decalcified like a woman during menopause. It's super interesting, actually, and then their digestive tract their gut regresses. Maybe that's just as well a breeding age. Freshwater eels get together in places where their usual food options like insects and small fish are probably rare or non existent. Out in the Atlantic Ocean, there's a region called the Sargasso Sea. Unlike the Mediterranean, the Red and most other seas, this one is not bordered by any land masses. Instead,

its borders are formed by strong ocean currents. Both American and European species of freshwater eels come here to reproduce. A research suggests that they might use magnetic fields as a navigation tool. The European eel has the longest path to travel. Some individ jewels transverse around five thousand miles or eight thousand kilometers to get there from Norway, half a world away. The freshwater eels that live in and around the Pacific Ocean have spawning areas of their own.

The Japanese eel is thought to breed at a site west of the Mariana Islands. Other species could be procreating somewhere between New Caledonia and Fiji. Eels release their eggs underwater to be fertilized by clouds of expelled sperm that goes for both freshwater eels and the non freshwater species such as the aforementioned moras and conger eels, speaking of which a derec explained that we know even less about

conger eels than anglids when it comes to reproduction. She said, but we think there is at least a spawning area in the Mediterranean Baby. Hopefully future research will shed some light on their private lives. Today's episode is based on the article how do eels reproduce? On how stuff works dot Com, written by Mark Mancini. Brain Stuff is production of I Heart Radio in partnership with how stuff works

dot Com and is produced by Tyler Clang. Four more podcasts from my heart Radio, visit the iHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.