The Atlantic Portuguese man o' war (Physalia physalis), also known as the Man-of-War, blue bubble, or floating terror, is a marine cnidarian of the family Physaliidae found in the Atlantic Ocean, as well as the Indian and Pacific Oceans. Its venomous tentacles can deliver a painful (and sometimes fatal) sting. Despite its outward appearance, the Portuguese man o' war is not a jellyfish but a siphonophore, which is distinguished from jellyfish in that it is not a single multicellular organism, but a colonial organism made up of specialized minute individual organisms called zooids. These zooids are attached to one another and physiologically integrated to the extent that they cannot survive independently and function as if they were an individual organism.