• Biodiversity Portuguese Man-of-War
  • Portuguese Man-of-War

    Physalia physalis

    Anyone who has spent time walking along the seashore looking for shells and enjoying the ocean will surely have seen the Portuguese Man-of-War (Physalia physalis). It goes by several names including the blue bubble, blue bottle, man-of-war, and the Portuguese man o’ war. But did you know that this tentacled, stinging organism is not a jellyfish? In fact, its not even a single organism, but a collection of four separate polyps.

    The Portuguese Man-of-War have specialized polyps and medusoids that make up the organism. Its the uppermost polyp, a gas-filled bladder (a pneumatophore), that these blue bottles are named after. But the painful stings come from the man-of-war’s second organism.
    Long tendrils that can reach 165 feet (50 meters) in length are covered in venom-filled nematocysts which are used to paralyze and kill fish. If you’re a human and you get stung, its very painful but rarely lethal.

    Next time you go out to the beach, remember that the Portuguese Man of War, while it may look like a jellyfish is really a collection of specialized hydroid polyps! Its a fun ecofact for you to impress your beach going friends with. Just make sure you don’t touch it, because even washed up blue bottles can pack a punch!

    For more information

    Information about Siphonophores, including information about life cycles, body plans and colonial organization: siphonophores.org

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    Written by Rob Nelson

    Rob is an ecologist from the University of Hawaii. He is also an award winning filmmaker. As principle director of the Untamed Science productions his goal is to create videos and content that are both entertaining and educational. When he's not making science content, he races slalom kayaks and skydives.

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