Rome residents planning a weekend by the sea along the coasts of Campania, western Calabria or the Aeolian Islands may want to think twice, as hordes of the Pelagia noctiluca jellyfish have already taken up residence. The pinkish jellyfish, which is also known as the mauve stinger, is the same species that invaded the port of Portofino in Liguria early last month. Its bell or umbrella can grow to 15cm, but the main problem for swimmers are its stinging tentacles, which grow up to four metres. As its Latin name suggests, the jellyfish also glows in the dark, emitting flashes of a greenish luminescence.

The jellyfish invasion is currently restricted to the southern Tyrrhenian sea, but Italy