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Rhinoceros SurpriseA Javan rhinoceros triggers a camera trap in Indonesia's Ujung Kulon National Park in late 2010. The image was released this week by WWF-Indonesia and Indonesia's National Park Authority. A motion-activated video camera also recorded "dramatic" footage of four of the rhinos, deemed critically endangered by the International Union for Conservation for Nature. At fewer than 40 individuals, the Javan rhino may be the rarest mammal on the planet, according to WWF.(See pictures: "14 Rarest and Weirdest Mammal Species Named.")Though the videos and pictures are "great news," the animals still face grave threats, WWF-US chief scientist Eric Dinerstein noted in a statement.For instance, an eruption of the nearby Anak Krakatau volcano could easily wipe out all life on the peninsula that the rhinos call home."There are no Javan rhinos in captivity," he said. "If we lose the population in the wild, we've lost them all."

Photograph courtesy Ujung Kulon National Park and WWF