Blue Bottle – Portuguese Man O’ War (Physalia utriculus)

Image of 3 bioluminescent Man O'Wars
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These beautiful creatures are commonly thought of as common Jellyfish; however, they are actually far more complex. Man o’ wars are composed of multiple organisms all working together!


The Blue Bottle man o’ war is actually what is called a siphonophore. Siphonophores are a colony of specialized minute individual organisms called zooids. These zooids share tissue and cannot survive independently.

Blue Bottle Man o' War - Split Water level view - Image Courtesy Matthew Smith

Image Courtesy Matthew Smith

The man o’ war has no means of propulsion, but has an air sack that keeps it near the surface where winds, tides and currents propel it around the Atlantic Ocean. They spend the majority of their time at the surface, but can submerge by deflating their air sack if attacked.

Deadly Sting

The man o’ war has a deadly sting. Their tentacles are composed of hundreds of bands of stinging cells. Some cells are specialized to feed while others for defense and stunning prey. They can be deadly to humans depending on where one is stung. A hand sting for most adults will be painful, but not deadly in most cases. A sting on thin-skinned areas of the body however could potentially be fatal.

Video Source: National Geographic

That said, ten thousand people are stung each summer by the man o’ war in Australia alone and deaths are rare. Detached stingers and/or a dead organism’s stingers can be just as painful as the living organisms.


Blue Bottle Man o' wars litter a beach. People are walking through them! Wow!

Image Source: Shutterstock



Several organisms prey on the man o’ war including the loggerhead turtle, the ocean sunfish, the violet snail, and a few sea slug species.



Learn more about the man o’ war by checking out our friends at Sci-Show, below:




Header image courtesy of Matthew Smith / DailyMail

Edited by: Reginald V. Finley Sr

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