There's no reason to be afraid. Sharks don't have lasers on their heads yet (that we've found), but we're getting closer and closer to discovering Dr. Evil's dream fish. Granted, you have to dive pretty deep to find the velvet belly lanternshark that uses lightsaber-like spines to warn off predators. Then again, we feel that the last half of that sentence makes the first half totally worth it. The shark's glowing spines are just half the story, though -- hit the jump and find out what else they can do.
The first in-depth study of the splendid lantern shark, a rare type of dogfish shark found mostly in the East China Sea and off the coasts of Taiwan and Japan, has revealed that the shark can glow in the dark and go "invisible." Both of these abilities are naturally occurring biological processes. The ability to glow, and hide itself in an invisibility "cloak," are controlled by light-emitting organs called photophores. Many species glow using bioluminescence, but coupling with the invisibility is particularly interesting. To become invisible, the photophores replace the down-welling light from the sun, which is absorbed by the shark's body. The silhouette of the shark then disappears when it is viewed from below. This is useful to help the shark hide from predators, staring up at it from the ocean's depths.
The US Military might not be looking to make veteran Marines glow with an eldritch green light, but they are looking into making other things glow by borrowing tricks from fireflies and plankton. And by "looking into" we mean funding university studies with grants. The big deal about bioluminescence is that it creates light without creating heat, making it invisible to infrared and other heat-seeking tech. Possible applications include "creating biodegradable landing zone markers that helicopters can spot even as wind from their rotors kicks up dirt," making "'friend vs. foe' identification markers and security systems, and methods to track weapons and supplies on the battlefield." And also being totally cool.