My favorite tank was the one in the ceiling. Looking from this angle you could see the underbellies of these magnificent creatures. As they bellow water through their bodies, these clear blobs pump water into themselves. The water seems to go into a narrow notch that looks something like a mouth. Their motion diffracts the light within the tank in a smooth green hue.
Jellyfish are graceful.
They don't hit the side of the tank. But at the same time, they don't mind bumping into each other as they glide across your view. I guess that's how they make friends. Maybe jellyfish are more than simple eating machines.