Nomad jellyfish

How it lives

It has two body forms. The free-swimming jellyfish reproduces sexually, and a small polyp that lives on the seabed reproduces asexually. Polyps can survive several years and can make cysts that give dense populations within weeks. In lab tests, young jellyfish are released mostly at 20 to 26 C, and release speeds up as Levantine waters warm, around mid-April. The species is recorded in waters of about 16 to 31 C. Summer swarms are common, and winter animals can be larger.

Where it goes

A drifter that goes where the currents carry it. Young jellyfish can travel about 200 to 300 km over 2 to 3 months, and the drift from Egypt to Israeli beaches takes about 55 to 60 days on average. In Cyprus, a local marine biologist quoted in the press said a visit can last from several days to 1 or 2 months, depending on temperature and waves.

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

Not evaluated by the IUCN. It is native to the Indian Ocean; DNA work links Mediterranean animals to ones from Tanzania. The first Mediterranean record was in 1977 off Israel, although a 1938 photo from Haifa port suggests it was there earlier. Large yearly swarms were common on the Israeli coast by the mid-1980s, and it later spread north-west to Turkey, Greece, Malta, Tunisia, Sicily and Sardinia. It is listed among the worst invasive marine species in European seas. In Cyprus, 2024 press reports placed sightings around Protaras and Paralimni and up to the Vasiliko power plant area. No reliable population count was found.