Jellyfish Return to Greek Waters, Raising Public Concern amid Heatwave

As Greece battles a fierce heatwave and crowds head to the coast for relief, jellyfish have made their seasonal return, sparking concern among swimmers and beachgoers.

The Hellenic Biodiversity Observatory has confirmed recent sightings of both the mauve stinger (Pelagia noctiluca) and the blue jellyfish (Rhizostoma pulmo) in several coastal regions across the country. In a recent announcement, the organization emphasized that these species have begun appearing in increasing numbers, signaling the start of a seasonal trend.

What You Need to Know About Blue Jellyfish

The Rhizostoma pulmo, or blue jellyfish, is a regular presence in Greek waters. According to the Observatory, its population tends to spike locally from late June through mid-July.

Key facts:
• It is among the largest jellyfish species found in Greece.
• Its sting is typically mild and not considered dangerous.
• Its appearance is natural and cyclical, with outbreaks far less intense in Greece than in neighboring countries.

Importantly, experts stress that the presence of blue jellyfish should not be viewed as an invasion or ecological threat. “If you encounter one at sea or washed ashore, observe it with interest and respect,” the Observatory advises.

However, swimmers are cautioned to avoid touching their face after close contact, as the jellyfish can release mucus that may cause mild swelling.

A Closer Look: Mauve Stinger vs. Blue Jellyfish
Though both species are now being spotted along Greek coastlines, they have distinct characteristics:

Mauve Stinger (Pelagia noctiluca):

• Small, bell-shaped body up to 12 cm in diameter with prominent spots.
• Color shifts from orange-brown in youth to pink or deep purple as it matures.
• Equipped with long tentacles that can exceed two meters in length.
• Known for a more painful sting compared to its blue counterpart.

Blue Jellyfish (Rhizostoma pulmo):

• Features a large, nearly hemispherical bell.
• Recognizable by a distinctive iridescent purple band around its edge.
• Its body ranges in color from milky white to vivid blue.
• Unlike the mauve stinger, it has thick, lobed arms instead of fine tentacles.