Photograph by Barry Kulick, Your Shot

Two manatees enjoy the warm waters at the head of Florida’s spring-fed Homosassa River. During cold snaps the docile marine mammals congregate en masse at such spots—but extreme freezes like that of January 2010 can still cause dozens of deaths. Manatees are born underwater and never leave it—though they must surface to breathe every few minutes. Much of their downtime is spent grazing on grasses—an adult can eat a tenth of its own 1,300-pound (600-kilogram) weight in just 24 hours.