The main similarities between koala and human digestive systems are the basic organs of oesophagus, stomach, liver, etc. Koalas have a different digestive system and metabolism which enables them to digest gum leaves. Eucalyptus leaves are tough, toxic and low in nutrition, but the koala has developed a stomach which is capable of removing the toxins from where they are filtered out by the liver. The caecum completes the process by changing the eucalyptus leaves into digestible nutrients. The caecum is similar to the human appendix.