Talk about an inner glow. The marine snail, Hinea brasiliana, radiates green light to startle predators, so the snail can make a quick—or at least relatively quick—get away. But there's a mystery to this bioluminescence: The snail's body sports just a handful of glowing cells, yet its entire shell lights up. To shed light on the puzzle, researchers shed some light on the snails. They focused a tight beam of light through the shell's opening, mimicking the light emitted from the animal's cells, and found that the entire snail lit up. The trick appears to be that the mollusk's shell scatters light. This allows the snail to turn a tiny glow into a much larger one, making it seem more formidable to predators. Understanding how the shell's internal structure produces this luminosity could inspire lighting designs of the future, the team reports  online today in the Proceedings of the Royal Society B.
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