Lantern sharks, a type of small dogfish sharks, are well known for their bioluminescence, indeed that is how they were given their name.  Researchers have recently discovered that the rare splendid lantern shark can adjust its coloration and lighting so as to become effectively invisible to predators.  Harry Potter apparently is no the only one with an invisibility cloak.

Lantern Sharks Can Become Invisible, Glow-In-The-Dark

 “The photophores replace the down-welling light from the sun, which is absorbed by the shark’s body,” lead author Julien Claes explained to Discovery News. “The silhouette of the shark therefore disappears when seen from below.”