The common name comes from a Portuguese war ship type of the 15th and 16th century, the man-of-war or caravel (in Portuguese, Caravela), which had triangular sails similar in outline to the bladder of the Portuguese Man o' War.
While the Portuguese Man o' War resembles a jellyfish, it is in fact a siphonophore – a colony of four kinds of minute, highly modified individuals, which are specialized polyps and medusoids. Each such zooid in these pelagic colonial hydroids or hydrozoans has a high degree of specialization and, although structurally similar to other solitary animals, are all attached to each other and physiologically integrated rather than living independently.
Such zooids are specialized to such an extent that they lack the structures associated with other functions and are therefore dependent for survival on the others to do what the particular zooid cannot do by itself.
A similar group of animals are the chondrophores, which are specialised hydroids that float at the surface of the open ocean.
The Portuguese Man o' War is infamous for having a painful sting, and for swarming in many hundreds.
Habitat and location.
The Portuguese Man o' War lives at the surface of the ocean, with its float above the water, serving as a sail, and the rest of the organism hanging below the surface. It has no means of propulsion, but is moved by a combination of winds, currents, and tides.
It is found in open ocean in all of the world's warm water seas but most commonly in the tropical and subtropical regions of the Pacific and Indian oceans, and the northern Atlantic Gulf Stream. Strong onshore winds may drive them into bays or on beaches.
Physalia physalis is found in tropical Atlantic waters and occasionally as far north as the Bay of Fundy and the Hebrides and also the Mediterranean Sea. P. utriculus (La Martiniere), commonly known as the bluebottle, occurs in the Pacific and Indian oceans.
They are reported abundantly off the Karachi coast in Pakistan, particularly at the Sandspit and Hawkes Bay beaches during the months of June, July and August, and are also common in the ocean off parts of Australia and New Zealand. During these months, they are also found to come ashore in the Sea of Cortez (Gulf of California) after rain, where they are known as agua(s) mala(s) by local Mexicans.
They are known to come ashore all along the northern Gulf of Mexico and both east and west coasts of Florida as well as around the Hawaiian Islands. They are also frequently found along the east coast of South Africa, on the KwaZulu-Natal beaches (particularly if the wind has been blowing steadily on shore for a number of hours) and on the Cape South Coast (Bettie's bay to Gans bay), also driven by onshore winds during winter storms. The Portuguese Man o' War has also been spotted in the Mediterranean sea, after first being spotted off the coast of Spain, later in Corsica.
In the summer of 2009, Pembrokeshire County Council warned bathers in its waters that the organisms had been sighted in Welsh waters.
In Ireland, there were dozens of confirmed sightings (in 2009-2010), from Termonfeckin in Co Louth to Ballymoney in Co Wexford.
There is also an abundance of Portuguese Men o' War in the waters of Costa Rica. Congregations of them can be found in the March and April months.
They are also found in Guyana, South America. They wash up on the seashore during certain months of the year.
It is rare for only a single Portuguese Man o' War to be found; the discovery of one usually indicates the presence of many as they are usually congregated by currents and winds into groups of thousands.
Attitudes to the presence of the Portuguese Man o' War vary around the world. Given their sting however, they must always be treated with caution, and the discovery of a number of blue bottles washed up on the beach might lead to the closure of a whole beach.
In 2010, sightings of the bluebottle were recorded around the small island of Malta in the Mediterranean.
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