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 ...

Under the Sea: The jellyfish galaxy JO206 trails across this image from the NASA/ESA Hubble Space Telescope, showcasing a colorful star-forming disk surrounded by a pale, luminous cloud of dust.