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").
Carybdea marsupialis
"Carybdea marsupialis" was once considered a widespread species found in warm oceans around the world. Taxonomic reviews have shown that most of these are other species in the genus "Carybdea", with the true "C. marsupialis" essentially restricted to the Mediterranean Sea. It is the only box jellyfish in this sea. It is pelagic and is present in the upper few metres of the sea.