Mother koala and young (Phascolarctos cinereus) in its mother's pouch. The young koala (left) is called a joey. The koala is an arboreal (tree- living) marsupial. At birth the young crawls into the pouch on the mother's belly. The pouch has drawstring-like muscles that the mother can tighten at will. The joey remains inside the pouch for about six months and feeds only on milk. After leaving the pouch it rides on its mother's back and continues to feed on milk and gum leaves for another six months. Photographed in Australia.