I'm reminded of one of my favorite books by Iain M. Banks - The Algebraist. Come to think of it there's another one too that has several sections devoted to creatures called Behemothers who live for millions of years inside air worlds that circle the galaxy. That one is called Look to Windward.
I was just about to comment on Wayne Barlowe. The inspiration is definitely there, and Barlowe was a concept artist on Avatar which was mentioned earlier in comments as well! This piece also reminds me of the Jovian gas beasts from the book "Our Universe" which had a section about what life might look like if it existed on other planets in the solar system.
Awesome painting I especially love the feeling of atmosphere.
Oh wow, these are amazing creatures! They sort-of remind me of the emperor sea strider from the documentary, alien planet, only an airborne version. Have you ever seen Wayne Barlowe's stuff? If you haven't, I recommend you take a peek, it's awesome
I'm guessing that they live in humungous planets made almost entirely out of gas, Jupiter, let's say. This could end up with an athmosphere almost as dense as water, or even more. I mean, in that quantity, the pressure would be... agh. I suck at physics. (And my english sucks too. I know)
If it's anything like Jupiter I'd imagine they'd be shredded by the thousand-mph winds or shocked to heck by the lightning that's something like 50 times the power of Earth's. And that's if they survive the overwhelming radiation, which, by the way, would kill a human in a day from over 660000 km away (surface of Jupiter's moon Europa).
As said, I don't know shit about physics ^ ^. I don't know. Let's just imagine it's a more stable gas planet, with a more still athmosphere and an amount of radiation that allows the existance of life. (Who knows, maybe these guys can handle radiation better than us).
hmm...maybe a planet like Uranus...no, probably still too dangerous. The problem with radiation from gas giants is that it tends to be strong enough to break or change molecular bonds, which makes it really hard for complex molecules like amino acids to form much less stay together. If it's silicon-based life, maybe the higher molecular weight would give it a better chance, but then silicon has the problem of less reactive, which makes it less likely to form chain or ring structures and makes it more brittle so chain-like structures would shatter more easily.
BabakoSen is completely right, in fact, it might make more sense for this animal to live on a smaller gas giant, or a earth size planet. However, it does discredit your work. This is an amazing piece and looks amazing.