European Eel (Anguilla anguilla)

The European eel is something of a puzzle. Humans have know about it, eaten it and studied it since Aristotle’s time, but much confusion still remains surrounding the eel and it’s mysterious sex life.

For the longest time eels were thought to spontaneously generate from mud, mainly due to the fact that their younger forms look nothing like the adult eel. It wasn’t until the late 1800s that the link was made between leptocephilli (larval eels) and the adult eel). The eel’s reproductive organs also remained a mystery, despite the long drawn out man hunt spanning from the 1700’s, even involving Sigmund Freud (yes, the psychologist) who’s first publication in 1876 was on his failure to find to the elusive gonads.

The gonads have since been found, but we still have no idea of where the eel spawns. It took one man, Johannes Schmidt, 9 solid years of trawling the sea to find that they might spawn in the Sargasso Sea. Scientists have tried and failed to track adults migrating from our rivers to their spawning ground. They are also incredibly difficult to breed, so any eels people eat are from wild populations.

Unfortunately, time might be running out for eels. Their populations are declining and the iucn has judged them to be critically endangered, so who knows if we’ll be able to solve the eel mystery before they’re gone.