Koalas, iconic marsupials native to Australia, possess a highly specialized diet. Their unique feeding habits are particularly evident in the developmental stages of their young. Understanding what baby koalas eat reveals a fascinating progression from exclusive milk consumption to a highly adapted diet of eucalyptus leaves.
The First Meal: Mother’s Milk
When a koala joey is born, it is incredibly tiny, measuring about 2 centimeters long and weighing less than a gram. It instinctively crawls into its mother’s pouch immediately after birth, where it attaches to one of two milk teats. The teat swells within its mouth, ensuring a continuous food source. For the first six to seven months of its life, the joey remains inside the protective pouch, relying solely on its mother’s milk. This period is essential for its early development, as it slowly grows fur, and its eyes and ears begin to form.
The Unique Weaning Process: Pap
Around 5 to 7 months of age, as the joey starts to emerge from the pouch, a crucial dietary transition begins with a specialized substance known as “pap.” Pap (also known as caecotrophs or faecal pap) is a soft, runny form of specialized droppings produced by the mother. It is distinct from regular koala faeces. Pap originates from the mother’s caecum, a pouch connected to the junction of her small and large intestines.
The joey consumes this pap directly from the mother’s cloaca. This process is vital for inoculating its sterile gut with microorganisms. These bacteria are essential for the joey to break down and digest the fibrous and toxic compounds found in eucalyptus leaves. Without this microbial transfer, the young koala would be unable to process its future diet. This transitional food also provides a rich source of protein, preparing the joey’s digestive system for the challenging adult diet.
A Lifetime of Leaves: Adult Koala Diet
Once fully weaned from milk and pap, koalas transition to an adult diet consisting almost exclusively of eucalyptus leaves. They consume between 200 to 500 grams of leaves daily. Despite the hundreds of eucalyptus species in Australia, koalas are selective, choosing only certain types based on factors like nutrient content and toxin levels.
Eucalyptus leaves are tough, fibrous, low in nutrition, and contain chemical compounds toxic to most other animals; to manage this challenging diet, koalas possess a highly adapted digestive system, including an unusually long caecum up to 200 centimeters long. This organ houses millions of bacteria that break down plant fiber and detoxify the leaves through fermentation. Their slow metabolic rate, contributing to their 18 to 22 hours of daily sleep, aids energy extraction from their low-calorie diet and toxin processing. Koalas also obtain most water from leaf moisture, rarely needing to drink.