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").
Cotylorhiza tuberculata
Cotylorhiza tuberculata is a species of jellyfish, of the phylum Cnidaria, also known as the Mediterranean jelly or fried egg jellyfish. It is commonly found in the Mediterranean Sea, Aegean Sea, and Adriatic Sea. It can reach 40 cm in diameter and is usually less than 17 cm wide. It seems that this jellyfish's sting has very little or no effect on humans. The cnidarian’s smooth, elevated central dome is surrounded by a gutter-like ring. Its marginal lappets are elongated and subrectangular. Each moutharm bifurcates near its base and branches several times. In addition to some larger appendages, there are many short, club-shaped ones that bear disk-like ends.
"C. tuberculata" are the most common jellyfish of their entire order in the Mediterranean Sea. They experience an annual life cycle marked by summer population blooms, which is likely an adaptive result of the strong seasonal changes in their Mediterranean environment. Their phases of development are quite similar to that of their other jellyfish counterparts. "C. tuberculata"s four main stages of growth include the swimming larvae known as planulae, younger, sessile polyps called scyphistomae, the undeveloped young adult intermediates known as ephyrae, and the adult jellyfish forms, called medusas. In a given year, planulae are present from August to November, scyphistomae are present perennially, ephyrae can be seen from May to August, and medusa are prominent from July to November.