Shy Eel Glows Bright Green, Possibly As a 'Sexy Charm'

But now, after hours spent studying the fluorescent proteins of two eels, the researchers have solved the mystery. "It started as a brain protein and then became this fluorescent protein in muscle," said study lead researcher David Gruber, an associate professor of biology at Baruch College in New York City. Once the protein made its switch from a neural to a fluorescent protein, it spread like crazy throughout the eel population.