This the the beautiful and colorful Pacific Sea Nettle. It is a "medusa-phase" of the gelatinous members of the subphylum Madusoza family. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient movement. The tentacles are armed with stingers and may be used to capture prey and defend against predators.