There’s a small species of shark, just about 17 inches long, that lives deep in the dark ocean. This is that section where it’s so deep and dark that practically the only light comes from the bioluminescence of the sea creatures swimming around. Living in this kind of dicey neighborhood and being only 17 inches long, the shark needs some protection from predators. Which is why it’s got long, creepy spines that look like the nails of some creature Tim Burton dreamed up.
But it’s dark down here, and the shark needs some way to let predators know what’s up. So instead of trying to slink away in the shadows, it lets everyone know what it’s packing. All along its back, the shark has rows of little photophores that light up its spines. Any predator comes close, it sees a flash of that blade and thinks twice about messing with this little guy.
In short, nerds were right all along: The secret solution to bullying truly is light sabers.
Glowing shark scares off predators with 'lightsabers', BBC.