Portuguese man-of-war

Portuguese man-of-war (Physalia physalis), colorful jellyfish of the order Siphonophora. It consists of an assemblage of four kinds of polyps, the most obvious of which is a gas-filled bladder about 1 ft (30.5 cm) long, which carries a high crest and is colored blue or purple. Below this float are supported other polyps, including the long, stinging tentacles used for catching prey. The sting can be painful to humans.