The tarsier, a small primate best known for its bulging eyes and quiet demeanor, has a secret: It's actually incredibly loud, particularly if you're a dolphin. Until recently, this fact was a mystery to humans because the tarsier has an ultrasonic scream, inaudible to human ears. Texas A&M anthropologist Sharon Gursky-Doyen stumbled across the find when she noticed that when the tarsiers opened their mouths to speak, she wasn't hearing anything. "She had the foresight to get hold of a bat detector, and she was able to get that vocalization on a recording," Ramsier said. The tarsiers now find themselves in an exclusive club in the animal kingdom. Bats, dolphins and whales are the best-known practitioners of ultrasonic communication, but some cats also use the high-frequency method to communicate with their baby kittens . via