Bluebottle (Physalia utriculus) washed up on a beach. Also known as the Portuguese man-of-war, this organism is a floating hydrozoan. It consists of a colony of four types of polyps with different functions. This polyp is the gas-filled float. Trailing behind it are its tentacles, which inflict a painful sting. Although rare, in severe human cases the victim may suffer cardiovascular and respiratory collapse. Photographed in South Africa.