Portuguese man o'war

Cnidarian

Identification & Biology

• IdentificationA small, free-swimming jellyfish with a mushroom-shaped, translucent bell that pulses to propel it through the water. The bell is spotted with pink to mauve-purple bioluminescent spots. Long, thin stinging tentacles trail behind.
• SizeBell diameter up to 12 cm. Tentacles can trail up to 2 m.
• Social HabitCan be solitary or in massive swarms numbering millions. One of the most common stinging jellyfish in the Mediterranean. Bioluminescent, producing flashes of light at night.
• HabitatOpen water (pelagic). Approaches coastlines seasonally, sometimes in enormous numbers. Often concentrated by currents and wind.
• Depth0 to 300 m. Found throughout the water column, migrating vertically.
• Feeds OnSmall fish, fish eggs, crustaceans, and other plankton caught on its stinging tentacles.
• DistributionWorldwide in warm and temperate oceans. Very common in the Mediterranean, including Maltese waters.
• DescriptionPelagia noctiluca (the mauve stinger) is the most common stinging jellyfish in Maltese waters and the species responsible for most jellyfish stings reported by swimmers. It can form enormous blooms that close beaches during summer months. The sting causes a burning sensation and a red rash that can last several days. It is bioluminescent, producing a beautiful mauve glow when disturbed in the water at night.