The purple sea snail Janthina janthina can be seen in many tropical seas, floating on the surface of the water, as long as it is warm! They have the curious ability to make a "raft" of air bubbles trapped in "drool" to keep themselves on the surface of the water, head down. they feed on hydrozoans, such as Portuguese man-of-war or animals close to jellyfish. Another curiosity: they begin their life as males, and pursue as females. Hawaï.