[DeanStevenson]

Fascinating how certain animals have evolved with complex migration patterns to breeding grounds. And unfortunate that 95% of the population has already collapsed.

Makes me wonder what the world was like before this last great extinction.

[Nzen]

tl;dr Eels have a long lifecycle with several stages. They do not develop sexual organs until late in their life, when they migrate back to the Saragossa Sea. This meant earlier autopsies of eels revealed no sexual organs, even though scientists could provoke them with hormone therapy. So, a team lead by Jose Azevedo tagged female eels in the Azores in 2018, and tracked them via satellite [0].

[0] https://www.nature.com/articles/s41598-022-19248-8

I sometimes think about the selection pressures that lead to complex life cycles, like fig wasps. I find myself thinking about it naively, like one existed and the other grew into the niche. But, realistically, everything is changing (slowly) all the time. I just notice it for, say, influenza because their cycle time is so short.

[jfengel]

The important part of the story is that it took so long. People actively searched for an answer for thousands of years.

The answer itself is interesting, but more remarkable to me is how doggedly people pursued it for so long. It seems so basic that they must reproduce the way other vertebrates do, and yet the lack of apparent organs was baffling.