The first glow-in-the-dark animals may have been ancient corals deep in the ocean

A new study suggests that the first animal that glowed in the dark was a coral that lived deep in the ocean about half a billion years ago. That's far earlier than previously thought. Today, marine creatures that glimmer include some fish, squid, octopuses, jellyfish, even sharks _ all the result of chemical reactions. Scientists used a remote-controlled underwater rover to study corals on the ocean floor. Using genetic data from 185 species, they found a common ancestor that lived 540 million years ago and very likely had the ability to glow. They reported their findings Tuesday.