Portuguese man-of-war (Physalia utriculus). Also known as a bluebottle, it is not one organism, instead being a colony of hydrozoan animals. Members of the colony have distinct roles. One individual forms the float (upper frame), which is filled with a mixture of nitrogen and carbon monoxide. Individual called gastrozooids are responsible for digesting food and passing it to the rest of the colony. Prey is captured by dactylozooids, which comprises a large stinging tentacle. Reproduction is carried out by gonozooids. The colony is planktonic, being carried around by ocean currents. It inhabits warm waters.