The freshwater jellyfish, or Craspedacusta sowerbyi, is a jellyfish that survives in freshwater immune system of a jellyfish is really just based on defending itself from other predators. When it is attacked, stinging threads uncoil quickly from its tentacles when it makes contact with another object. This reaction then spreads to the rest of the same tentacle making contact with the other object. Finally, the jellyfish then releases a toxin that can either paralyze or kill another predator. This action comes in handy when the jellyfish is going to consume another species.