PORTUGUESE MAN OF WAR (JELLYFISH)
Despite its outward appearance, the Portuguese man o' war is not a common jellyfish but a siphonophore, which is not actually a single multicellular organism, but a colony of specialized minute individuals called zooids. These zooids are attached to one another and physiologically integrated to the extent that they are incapable of independent survival. The Portuguese man o' war is composed of three types of polyps and an associated gas-filled air sac called a pneumatophore or "sail". The pneumatophore should probably not be considered a polyp as it develops from the planula, unlike the other polyps. This sail is bilaterally symmetrical, with the tentacles at one end. It is translucent, and is tinged blue, purple, pink, or mauve. It may be 9 to 30 cm (3.5 to 11.8 in) long and may extend as much as 15 cm (5.9 in) above the water. The Portuguese man o' war generates carbon monoxide in its gas gland, filling its gas bladder with up to 14% carbon monoxide. The remainder is nitrogen, oxygen, and argon, atmospheric gases that diffuse into the gas bladder. Carbon dioxide occurs at trace levels. The sail is equipped with a siphon. In the event of a surface attack, the sail can be deflated, allowing the organism to briefly submerge.