Mauve Stinger

A mauve stinger, Pelagia noctiluca, drifting over pale sand. Its species name combines the Latin words for night and light, and it earns it: when waves or a passing boat jostle it after dark, it gives off flashes of bluish light, and a startled one can leave a trail of glowing mucus behind. It is mostly an open-ocean jellyfish, but swarms are blown inshore in the Mediterranean and eastern Atlantic, and the sting is painful, so this is one glow to admire from a boat rather than up close.