Biology/Natural History: Spends much the time motionless or slowly pulsing the bell while drifting with tentacles extended 10-20 feet or more. Feeds on gelatinous zooplankton, especially other medusae. Usually with symbiotic amphipods on the subumbrella and juvenile crabs on the exumbrella, including Cancer gracilis. Also hosts the barnacle Alepas pacifica and juvenile fishes. Has only a mild sting. In the life cycle, fertilized eggs develop into ciliated planula larvae which swim, then settle and metamorphose into scyphistomae polyps. Mature scyphistomae had 30-44 tentacles and reproduce asexually by side budding as well as strobilating to produce ephyrae which grew up into mature medusae. In the laboratory it took about 9 months for an ephyra to grow into a mature medusa.