A shark with a lightsaber? What more could you possibly want? Researchers have found that the velvet belly lanternshark (Etmopterus spinax) uses “lightsaber-like” spines in order to ward off potential predators.
This variety of lanternshark is just a little guy. The largest of the species tops out at around 60cm in length, though most adults rarely exceed 45cm. You can see why wielding the preferred weapon of the Jedi Knights might come in handy from time to time.
Living in the depths of the ocean—in the mesopelegic zone between 200 and 1,000 meters deep—being armed in such a manner comes in handy. Two long, bioluminescent spines, one just in front of the dorsal fin, one just to the rear, act as a warning to bigger predators that might want to make a meal out of our little friend. Visible from several meters away, the glow-in-the-dark effect points out the spines, letting others know that taking a bite out of this particular shark will likely hurt a great deal. The prospect of imminent pain is enough to dissuade most interested parties.
Not only does the velvet belly’s bioluminescence help keep it safe from predators, it also helps with hunting creatures further down the food chain from itself. The shark has photophores along its underside that also illuminate. It uses these cells to camouflage itself in the sun. From below, the shark blends into the light coming from the surface, rendering it functionally invisible. Any shadow the creature casts is negated, giving it the chance to strike when it comes across a tasty meal. This is a similar strategy as aircraft painted blue on the bottom, to help them blend into the sky above.
Etmopterus spinax is certainly one tricky little bastard.