RiverWorld- Hunt of the Storm Riders

Welcome to a completely new world. I like to call this one RiverWorld.
Some time ago, scientists found entire moons and planets made entirely of water. Imagine it: a vast, never-ending sea composing the entire horizon. Nothing but a vast blue. Forever. Could life possibly develop on a world such as this. If enough of the right meteors and asteroids landed, and those minerals were hot enough, then yes. Multicellular life could potentially live on a place such as this. What types of creatures could live here?
Well, here's a concept. This one is called a Storm Rider. It has a large gas bladder, much like those in salmon on earth. These, however, are hundreds of times bigger, and can actually lift the peculiar beasts out of the water for some time. As they float around, they let their long, lofty limbs dangle downwards into the vast blue sea below. They drift sleepingly along until they grab something. Then the unfortunate animal snatched is yanked out of the water and drawn to the Storm Rider's waiting mouth. Not very crafty or clinical, but it might hold the record for the largest creature ever to fly with his sixty-foot long bladder.
Sketched in Pencil, Rendered in Photoshop.