SOLVED. SF Book Set on Another Planet with Airborne Natives [s]

[Bargle]

The book is set on another planet where there are 2 native intelligent species. One species floats in the air. I think they are similar to jellyfish. The species are in conflict with each other. Human explorers land on the planet. Inadvertently, they discover that when killed, the floating species release something (a dust or gas?) that causes humans to become extremely aroused and begin having sex with whoever is at hand. Eventually the humans ally with the floating species and provide them with weapons specially designed for them on Earth.

Carl Sagan makes a cameo appearance early in the book. He is quite elderly at the time of the story. The book was written well prior to Sagan's death, so it probably came out no later than the early 90s and may have been even from the early 80s.

[Andy]

Jem by Fred Pohl

[Bargle]

That's it. Thanks, Andy.

[Andy]

You're welcome. I read it just last year...