|A Blue Bottle washed ashore at a beach in Australia|
(La Martinière, 1787)
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. Also, like the Portuguese Man o' War, Physalis utriculus is not a jellyfish but a siphonophore, meaning that it is not a single animal, but a colony of tiny specialised organisms called zooids. The zooids that make up Physalia utriculus are all attached to one another and are linked to the extent that they all depend on each other for survival.
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.
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. On the east coast of Australia 10,000 to 30,000 stings from animals of the genus Physalia per year 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.
- "Indo-Pacific Portuguese Man-Of-War" (PDF). Marine Life Profile. Waikïkï Aquarium at the University of Hawai‘i-Māno. 1998. Archived from the original (PDF) on 2013-11-15. Retrieved 2009-01-12.
- "Bluebottles and Pacific man-o-war". Stinging jellyfish in tropical Australia. CRC Reef Research Centre. November 2004. Archived from the original on 2014-03-17. Retrieved 2009-01-12.
- "Bluebottle factsheet". Western Australian Museum. Archived from the original on 21 March 2015. Retrieved 12 August 2015.