The pelagic jellyfish (pelagia noctiluca) is the typical Mediterranean jellyfish. This species of jellyfish is widely present in all warm and temperate waters, such as the Mediterranean Sea, the Red Sea, or the Atlantic Ocean. Colonies of this "sea nettle" invade or run aground on beaches of the Mediterranean coasts where it has become since the 2000s the terror of bathers. The proliferation of this species, favored by the high water temperature and the limited number of predators, explains why it can invade ports and kill fish fauna.
It is a stinging jellyfish whose bite causes for swimmers a burning sensation, itching, relatively large skin lesions, even allergies which can cause anaphylactic shock. If it is not particularly dangerous, it is feared and proliferates more and more to the point that some beaches are equipped with protective nets.