Kefi Divers

Upside Down Jellyfish

These unusual jellyfish spend most of their time pulsing gently on sandy seabeds with their bell facing downward. Their distinctive behavior makes them one of the most fascinating creatures to observe in shallow Cretan waters.

Habitat: Shallow sandy bays, seagrass margins, warm lagoons

Best season: May - October

In Crete

The upside down jellyfish is a Lessepsian migrant that entered the Mediterranean through the Suez Canal. First spotted in Cretan waters in recent years, they've established populations in warm, shallow bays along the north coast. Their presence reflects the ongoing warming of Mediterranean waters and the changing marine ecosystem.

Behaviour

Unlike typical jellyfish, Cassiopea rest upside down on the seabed, pulsing gently to circulate water over their oral arms. They host symbiotic algae (zooxanthellae) in their tissues, which photosynthesize and provide much of their nutrition – essentially making them solar-powered. They can release stinging mucus into the water even without direct contact.

Diving tips

Look for them in shallow, sandy areas with good sunlight penetration. They're often found in clusters near seagrass margins. Avoid touching them or disturbing the sediment nearby as they release stinging cells into the water. Excellent subjects for photography due to their stationary nature. Keep a respectful distance to avoid the irritating mucus they release.