Nomad Jelly

Rhopilema nomadica

Rhopilema nomadica is a jellyfish found in tropical warm waters of the Indian and Pacific Oceans, and since the 1970s, it has also been recorded in the Mediterranean Sea due to Lessepsian migration through the Suez Canal. This species has a light blue body with a rounded bell that can reach weights of up to 10 kg. The bell typically measures between 40 to 60 cm in diameter, but some individuals can grow as large as 90 cm. Its presence in the Mediterranean has raised concerns as it is listed as one of the worst invasive marine species in European waters. These jellyfish thrive in a range of water temperatures, surviving from 16 to 31 degrees Celsius. They are commonly found in pelagic environments and have been recorded at various depths, with most occurrences being shallower than 40 meters. R. nomadica primarily feeds on plankton, which it captures using its venomous stinging cells located in its mouth arms. During the summer months, they tend to form large swarms, which can lead to painful encounters for divers and beachgoers alike. Reproduction occurs through a complex life cycle that starts with the adult medusa laying eggs, which develop into free-living larvae. These jellyfish can cause significant socioeconomic issues, particularly in regions like Israel, where their swarming behavior has resulted in reduced beach attendance and substantial financial losses. Their ability to clog seawater intake systems poses additional challenges in coastal management.