The Portuguese man-of-war is a deadly floating colony of tiny animals

This sea-dwelling creature goes by a myriad of other names: the blue bubble, floating terror, or just plain old man o’ war. Commonly mistaken for a jellyfish, it is in fact a marine cnidarian of the family Physaliidae.

Physaliidae is the family name given to a group of organisms that float on the surface of the Atlantic Ocean, moving around by aimlessly drifting on the waves. Although the mysterious creature does look very much like a jellyfish, it couldn’t be more different. Unlike jellyfish, which are single multicellular organisms, the man of war is made up of separate individual creatures known as zooids (small animals that form colonial animals). They are so dependent on one another they would not be able to survive away from the colony.


The large bubble-like head act as a sail, catching the wind the helping to move the animal along


The man-of-war is responsible for as many as 10,000 stings in Australia each summer causing severe pain and swollen welts in its victims. Stings have been known to cause death in some, but this is extremely rare. Less rare however, is pain continuing for up to three days and fever-like symptoms.

Although the same can’t be said for their unfortunate prey, when hunting their long tentacles are used to latch on and subdue young fish and crustaceans. If you were to look closely at the tentacles you would see lots of small nematocysts. These are small hollow structures that function like hypodermic needles, harpooning surfaces they come into contact with and administering the strong venom.


These creatures are often found washed up on beaches but it is best to leave well alone


It would be possible to mistake these non-jellyfish for colourful plastic bags floating in the ocean. The best thing you can do should you come across one is to avoid it entirely as they are even able to sting when they are dead. If you are interested in finding out more about how not to get stung by one, check out this article for the four key rules to follow (and if you do get stung – no, you shouldn’t pee on it).



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Photographs: Mary WitzigU.S. Fish and Wildlife Service Southeast Region4Neus