Physalia utriculus

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Physalia utriculus
A Blue Bottle washed ashore at a beach in Australia
Scientific classification
Kingdom: Animalia
Phylum: Cnidaria
Class: Hydrozoa
Order: Siphonophora
Family: Physaliidae
Genus: Physalia
Species: P. utriculus
Binomial name
Physalia utriculus
(La Martinière, 1787)
Stranded Blue Bottle Jellyfish with its typical blue tentacle.

Physalia utriculus, also called Blue Bottle or (Indo-Pacific) Portuguese Man-of-War, is a marine hydrozoan of the order Siphonophora found in the Indian and Pacific oceans. A gas filled bladder allows it to float on the surface, propelled by currents, tides, and by a sail at the top of the bladder, which may be left or right-handed. A single long tentacle of venomous cnidocytes, hanging below the float, provides the animal with a means of capturing prey.

P. utriculus is distinguished from the Atlantic Portuguese Man o' War (Physalia physalis) by the smaller size of the float (six inches compared to twelve) and by having a single long fishing tentacle. Like its larger relative, P. utriculus often occurs in swarms.


A bluebottle floating in Australia's eastern coastal waters (entangled with seaweed)

P. utriculus is less widely distributed than the larger P. physalis, but it is the most common species on Australian coasts. It is also found in Hawaiian waters, where it is informally named ‘ili mane‘o or palalia.[1]


Individuals of P. utriculus sometimes become stranded on beaches, where their toxic nematocysts can remain potent for weeks or months in moist conditions. P. utriculus is responsible for most of the reported injuries on Australian beaches, where up to 30,000 stings are reported. Most of the incidents are on the eastern coast, with only 500 or so in western and southern waters. Unlike P. physalis, no fatalities have been recorded for P. utriculus stings.[2]


Each individual is actually a colony of four specialized polyps and medusoids.


  1. ^ "Indo-Pacific Portuguese Man-Of-War". Marine Life Profile:. Waikïkï Aquarium. 12/98. Retrieved 2009-01-12.  Check date values in: |date= (help)
  2. ^ "Bluebottles and Pacific man-o-war". Stinging jellyfish in tropical Australia. CRC Reef Research Centre. November 2004. Retrieved 2009-01-12.