Digestion and Metabolism of the Koala :: Microbiology Marsupials Essays

Digestion and Metabolism of the Koala Koalas’ diets consist solely of Eucalyptus, which has many defensive mechanisms to deter herbivores. The foliage contains chemicals that are toxic and interfere with digestion, such as condensed and hydrolysable tannins, phenolic compounds, cyanogenic glycosides, and essential oils. The leaves also contain low concentrations of nutrients, making it even more difficult for the extraction of nutrients. In order to obtain the maximum amount of nutrients, koalas select leaves that have high nitrogen content, minimum levels of water and essential oils, and low in condensed tannins. The amount of nutrients absorbed in the gut is dependent on mastication due to the small size of the stomach. The cecum of the koala is 1.3 meters in length and has 8 to 14 folds, allowing epithelial relationships with 45 different species of bacteria. Tannin-protein-complex-degrading enterobacteria, one of the most important species, degrades tannin-protein complexes to remove nitrogen for absorption in the cecum. Juvenile koalas must obtain microflora by ingesting a special form of feces, called pap, from the mother. Introduction Koalas, Phascolarctos cinereus, are classified in the Order Diprodontia of Marsupiala. The major distinguishing characteristics of Diprodontia are syndactyl hind feet, forcipate forepaws, and one functional pair of incisors in the lower jaw (Martin and Handasyde, 1999). Koalas live in the eastern portion of Australia, from coastal and inland Queensland, through New South Wales, and on to Victoria. Among koalas, the size of the animal increases southward. Male koalas in Victoria weigh from 9.5 to 14.9 kilograms, while in Queensland, they weigh 4.2 to 9.1 kilograms. This trend also occurs in the female populations. In Victoria, females can weigh 7 to 11 kilograms and in Queensland can weigh 4.1 to 7.3 kilograms (Martin and Handasyde, 1999). Three subspecies of koala have actually been classified due to the difference in size and fur color. P. cinereus victor is found in southern Australia and is characterized by thick cinnamon-colored fur and is the largest of the koalas. P. cinereus cinereus is found throughout the koala range and has mixed gray fur.