Box jellyfish
In Australia (mainly northern; however, box jellyfish can live in subtropical waters as far south as Sydney, with "Carybdea marsupialis" being recorded as far south as Bermagui, Sapphire Coast) the highest risk period for the box jellyfish is between October and May, but stings and specimens have been reported all months of the year. Similarly, the highest risk conditions are those with calm water and a light, onshore breeze; however, stings and specimens have been reported in all conditions.
Phacellophora camtschatica
This cool-water species can be found in many parts of the world's oceans. It feeds mostly on smaller jellyfish and other gelatinous zooplankton, which become ensnared in the tentacles. Because the sting of this jellyfish is so weak, many small crustaceans, including larval crabs ("Cancer gracilis") and Amphipoda, regularly ride on its bell and even steal food from its oral arms and tentacles. The lifecycle of this jellyfish is well known, because it is kept in culture at the Monterey Bay Aquarium. It alternates between a benthic stage attached to rocks and piers that reproduces asexually and the planktonic stage that reproduces sexually in the water column; both males and females occur in the plankton.