From Ancient Greece to the 20th century, Aristotle, Freud, and numerous other scholars were all looking for the same thing: eel testicles. Freshwater eels could be found in rivers across Europe, but no one had ever seen them mate and no researcher could find eel eggs or identify their reproductive organs. So how do eels reproduce, and where do they do it? Lucy Cooke digs into the ancient mystery. [Directed by Anton Bogaty, narrated by Adrian Dannatt, music by Jarrett Farkas].

Lucy Cooke: No one can figure out how eels have sex

No one can figure out how eels have sex

The enigmatic life of eels begins in the Bermuda Triangle, defying centuries of myths with a journey from salt to freshwater.

Adapting from ocean wanderers to freshwater dwellers, eels undergo one of nature's most remarkable transformations and migrations.

Despite advances, the breeding secrets of eels remain elusive, with their Sargasso Sea rendezvous shrouded in mystery and intrigue.