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").
Crossota millsae
"Crossota millsae" was first described from the Pacific Ocean off Hawaii and California. It was subsequently found in the Arctic Ocean and in Guayanilla Canyon off Puerto Rico. NOAA researchers who filmed this species in 2018 near Puerto Rico called it a "psychedelic" jellyfish. It lives below 1 km depth in all four regions. Its highest abundance is found at 2500 m off California and 1250 m off Hawaii. In the Arctic Ocean, it has been observed sitting on the seafloor.