[delibes]

Gas giants are a much less obvious place for native life to evolve, at least from our understanding of life. Enceladus appears to have liquid water, which makes it much more likely (still slim).

That said, Arthur C Clarke included giant city-sized lifeforms floating in the clouds of Jupiter in his 2001, 2010, 2061 series. And Isaac Asimov wrote "Victory Unintentional" in the robots series.