Box jellyfish
Although the notoriously dangerous species of box jellyfish are largely restricted to the tropical Indo-Pacific region, various species of box jellyfish can be found widely in tropical and subtropical oceans, including the Atlantic Ocean and the east Pacific Ocean, with species as far north as California ("Carybdea confusa"), the Mediterranean Sea ("Carybdea marsupialis") and Japan (such as "Chironex yamaguchii"), and as far south as South Africa (for example, "Carybdea branchi") and New Zealand (such as "Copula sivickisi").
Thimble jellyfish
The thimble jellyfish swims constantly by pulsating its bell, rotating as it moves. It forms swarms in warm seas near the surface of the water. Aggregations have been reported covering a million square metres . The jellyfish feeds on plankton, drawing a water current past its outstretched tentacles by pulsating the bell. When edible zooplankton are encountered, they are immobilised by the cnidocytes (stinging cells) and passed by the tentacles to the mouth on the underside of the bell. Thimble jellyfish are consumed by fish, sea turtles and other predators.