A luminous jellyfish with long trailing tentacles is a beautiful sight, as long as a scuba diver sees it in time to avoid contact. These scuba divers were finishing a dive in Akumal, Mexico and making ...

Then there are lightmaking fish, squid, jellyfish, shrimp, the aforementioned ctenophores, several types of worms, and sea cucumbers. There are luminous siphonophores—sinister, stringlike ...