If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
The aim of jellyfish is to collect all the fish in the water, and avoid the bar objects like boots and buckets. You have 30 seconds to complete each level, if you are happy with what you have collected before the time is up, you can press space to advance to the next level, by doing this you will receive a score bonus. You control your jellyfish with the mouse and you can detach all items by clicking.
Mouse- To control the jellyfish.
Space bar- To advance to the next level.