Portuguese Man o' War

Portuguese Man o' War battle analysis

The Portuguese man o' war is one of the ocean's strangest fighters. What looks like a single jellyfish is a colony of genetically identical zooids, each with a job: one forms the float, some carry stinging tentacles, others digest prey or reproduce. Together they behave as one organism, drifting on the sea surface under a translucent blue or violet sail.

Its weapon is reach. Fishing tentacles average about 10 m and can trail as far as 30 m, and each carries huge numbers of nematocysts, tiny capsules that fire venom on contact. Small fish that swim into the curtain are paralysed and hauled up to the feeding polyps. For larger animals, including people, a brush with the tentacles means severe burning pain and welts; deaths have been recorded but are rare. On the absolute battle scale, that makes it a formidable passive trap rather than a killer of large animals.

Everything else is a weakness. It cannot swim, steer, see or think, and its body is soft. Its only escape trick is to deflate the float and sink for a while. Loggerhead turtles eat it through thick skin, ocean sunfish take it, blanket octopuses tear off its tentacles to use as weapons, and a small blue sea slug even recycles its stinging cells. The man o' war scores very high in Special and Weaponry, but in Agility and Intelligence it sits at the bottom of the roster.

Habitat & range

It lives at the surface of the open ocean, mainly in the Atlantic Ocean and the Indian Ocean in warm and temperate waters, and is regularly blown onto coasts. It has also appeared in the Mediterranean, where scientists have asked whether it is an occasional visitor or an established presence. Strandings are strongly driven by wind direction and strength.

Diet & hunting

It feeds mainly on small fish and fish larvae, plus other small drifting animals caught by the tentacles. It is itself eaten by loggerhead sea turtles, ocean sunfish, the blue sea slug Glaucus atlanticus (which stores the unfired stinging cells in its own body for defense) and blanket octopuses (which tear off tentacles and carry them as weapons). The man-of-war fish Nomeus gronovii is partly resistant to the stings and lives among the tentacles.

Social life

Not social in the usual sense. Each colony is one organism made of many zooids. Large numbers can drift together because wind gathers them, sometimes 1,000 or more according to NOAA.

Conservation

Not Evaluated: no IUCN Red List assessment was located in this pass. The species is widespread and abundant, with frequent mass strandings.

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