Unlike kangaroos

Unlike kangaroos and eucalyptus-eating possums, koalas are hindgut fermenters, and their digestive retention can last for up to 100 hours in the wild, or up to 200 hours in captivity.[46] This is made possible by the extraordinary length of their caecum—200 cm (80 in) long and 10

cm (4 in) in diameter—the largest proportionally of any animal.[50] Koalas can select which food particles to retain for longer fermentation and which to pass throu

gh. Large particles typically pass through more quickly, as they would take more time to digest.[46] While the hindgut is proportionally larger in the koala than in other herbivores, only 10% of the animal’s energy is obtained from fermentation. Since the koala gains a low amo

unt of energy from its diet, its metabolic rate is half that of a typical mammal,[45] although this can vary between seasons and sexes.[46] They are able to digest the toxins present in eucalyptus leaves due to their production of cytochrome P450, which breaks down these po

isons in the liver.[51][52] The koala conserves water by passing relatively dry faecal pellets high in undigested fibre, and by storing water in the caecum.[48]