Portuguese man o' war

Naming

The name "man o' war" comes from the man-of-war, an 18th-century sailing warship, and the cnidarian's resemblance to the Portuguese version at full sail. In Australia, South Africa and New Zealand, they are also referred to as Blue Bottles.

Habitat

The Atlantic Indian Portuguese man o' war lives at the surface of the ocean. The gas-filled bladder, or pneumatophore, remains at the surface, while the remainder is submerged. Portuguese man o' war have no means of propulsion, and move driven by the winds, currents, and tides.

Strong winds may drive them into bays or onto beaches. Often, finding a single Portuguese man o' war is followed by finding many others in the vicinity. They can sting while beached; the discovery of a man o' war washed up on a beach may lead to the closure of the beach.

Food

The Portuguese man o' war is a carnivore. Using its venomous tentacles, a man o' war traps and paralyzes its prey while "reeling" it inwards to the digestive polyps. It typically feeds on small marine organisms, such as fish and plankton.

Predators

The organism has few predators of its own; one example is the loggerhead turtle, which feeds on the Portuguese man o' war as a common part of its diet. The turtle's skin, including that of its tongue and throat, is too thick for the stings to penetrate.

The blue sea slug ''Glaucus atlanticus'' specializes in feeding on the Portuguese man o' war, as does the violet snail ''Janthina janthina''.

The blanket octopus is immune to the venom of the Portuguese man o' war; young individuals carry broken man o' war tentacles, presumably for offensive and/or defensive purposes.

The ocean sunfish's diet, once thought to consist mainly of jellyfish, has been found to include many species, the Portuguese man o' war being one-such example.

Defense

This species is responsible for up to 10,000 human stings in Australia each summer, particularly on the east coast, with some others occurring off the coast of South Australia and Western Australia. One of the problems with identifying these stings is that the detached tentacles may drift for days in the water, and the swimmer may not have any idea if they have been stung by a man o' war or by some other less venomous creature.

The stinging, venom-filled nematocysts in the tentacles of the Portuguese man o' war can paralyze small fish and other prey. Detached tentacles and dead specimens can sting just as painfully as the live organism in the water and may remain potent for hours or even days after the death of the organism or the detachment of the tentacle.

Evolution

Despite its appearance, the Portuguese man o' war is not a true jellyfish but a siphonophore, which is not an individual multicellular organism, but a colonial organism made up of many specialized animals of the same species, called zooids or polyps.

These polyps are attached to one another and physiologically integrated, to the extent that they cannot survive independently, creating a symbiotic relationship, requiring each polyp to work together and function like an individual animal.