National Geographic : 2016 Jan
PHOTO: DAVID GRUBER. ART: MARC JOHNS Science EXPLORE Sharks Go With the Glow CATS DIG THEIR OWN KIND OF MUSIC People who leave the radio on for their cat while they ’re out aren’t doing Tabby a favor, a recent study suggests. Researchers tracked how cats respond to music for humans versus music composed with the high pitch of feline voices and the tempo of purring or suckling. Cats mostly ignored classical works and overwhelmingly responded to the tunes created for them, in some cases even rubbing against the speaker. “ We’re trying to get people to think more carefully about why they ’re playing music,” says University of Wisconsin psychologist Charles Snowdon, “and who it’s really benefiting.” —A . R. Williams Marine biologist David Gruber specializes in finding life-forms that biofluoresce— creatures whose uniquely structured skin absorbs undersea deep-blue light and reemits it as neon green, red, or orange. Gruber, whose work is supported by the National Geographic Society, has found biofluorescence in jellyfish, corals, a sea turtle, and more than 200 fish and shark species. Now the diver-scientist is expanding his research beyond how these fish look to explore how they see. Gruber had a Cornell University eye specialist examine a “brilliantly fluorescent” swell shark (above). Humans’ eyes see a broad spectrum of colors. This shark “sees only in the blue-green range,” Gruber says, but in that range it sees acutely. Armed with an underwater camera that mimics the shark’s vision, he hopes to learn how biofluorescence helps the shark with camouflage, mating, and more. Meanwhile, Gruber says, the shark’s-eye-view camera fosters “a sense of empathy with these animals, to see how they see the world.” —Patricia Edmonds Gruber photographed this shark with a biofluorescent camera that casts a blue light, which the shark’s skin reemits as green.