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The natural world, filled with competition for resources and hostile climates, can be tough on animals. In order to survive, animals have had to adapt in surprising ways. Okapi, for example, have scent-glands on their feet to mark their territory. Wood frogs freeze their bodies.A wood frog in the Medvednica mountain forest.Nikola Solic
To survive the winter, up to 60 percent of Alaskan wood frogs'...