Koala joeys Bai'yali and Holly, at Taronga Zoo in Sydney, Australia. The poor eyesight of koalas has led to the species evolving to greet through nose touching and is a common way for koalas to determine if they are encountering a friend or a foe.
Koalas are marsupials and solitary creatures, spending most of their days comfortably lounging in trees. They usually spend between 18 and 22 hours, or about 75 percent of the day, sleeping. The extended naps help koalas conserve energy, which they need t