While creating the boukalizoans and helicozoans for the Gas Giant contest at [link] I came up with a ton of other creatures inhabiting the planet. I've decided to keep going with this theme and create my own gas giant ecology.
I haven't fully fleshed out the world itself, though I know it is a giant very similar to Jupiter with a thin ring made of ice and planetary debris, as well as numerous moons. The planet itself is called Coatlicue after the Aztec mother-goddess.

This creature is the Foliose Skydart, Astronavigator glaciophagus, nicknamed the "Star Duck" by researchers due to its kind of goofy-looking rostrum. The skydart spends its life traveling between the upper atmosphere of Coatlicue and the ice balls that make up the inner ring. The animal's entire body is covered in tough, vacuum-proof armor that also provides some protection from random space debris. The long, whip-like tendrils on the star duck's anterior end are sensors that help it locate the ring via the interference it creates in Coatlicue's magnetic field (many of the ice balls contain iron deposits from exploded moons). The skydart propels itself through space with what is, in essence, an organic jet propulsion system created by burning organic rocket fuel obtained from organisms in the planet's atmosphere. Oxygen for this combustion reaction is produced by the branching, photosynthetic microorganisms that cover the skydart's back.
Upon landing on an ice body, the skydart's "beak" actually splits into several stylets that anchor it in place while it rasps at the surface with a radula-like tongue to obtain ice, iron and other nutrients from the ground. Before returning to the gas giant, the sky dart also lays a small clutch of eggs on the ice body.

In addition to the photosynthesizers, there are also hundreds of other kingdoms of microorganisms with a wide variety of metabolisms lying dormant within the branches of the forest on the skydart's back. If a branch is broken off, some of these organisms will awaken and begin to metabolize, thus creating a miniature ecosystem much like a bacterial mat on Earth. Exactly which microorganisms awaken depends on local conditions. The colony in the upper left was collected in the upper atmosphere of Coatlice. It is composed primarily of "bacteria" that utilize magnetic fields for their metabolism, coupled with creatures that produce sacs full of bouyant gas to keep the colony afloat. The one on the right was found growing on the shores of a hydrocarbon lake on Huitzilipochtli, a moon with an atmosphere. This colony is a fungus-like organism that feeds directly from the methane and ethane saturating the ground.