Portuguese Man o' War

The Portuguese Man o' War, also known as Physalia physalis, is a jelly-like marine invertebrate of the family Physaliidae. Although it looks like a jellyfish, it is a siphonophore because it is a colonial organism made up of many minute individuals called zooids. It has long stinging tentacles that can reach length of 45 meters. As their tentacles are highly toxic, people will feel extremely painful after being stung. If they don't receive treatment in time, they may die.