详细介绍：Despite needing 18-21 hours of sleep a day , koalas are still capable of startling displays of energy, agility and aggre…Despite needing 18-21 hours of sleep a day , koalas are still capable of startling displays of energy, agility and aggression--especially around mating season. Get a closer look at the surprisingly rich and unexpected hidden lives of these iconic Australian marsupials in their natural habitat.详情