The Atlantic Portuguese man o' war (Physalia physalis), also known as the man-of-war, or floating terror, is a marine hydrozoan of the family Physaliidae found in the Atlantic Ocean, as well as the Indian and Pacific Oceans. Its venomous tentacles deliver a painful sting, which on extremely rare occasions has been fatal to humans. Despite its outward appearance, the Portuguese man o' war is not a jellyfish but a siphonophore, which, unlike jellyfish, is not a...