There are three major biomes in Australia. Each has it's own organisms and climate.
Tropical: this consists of a closed-canopy rain forest or eucalyptus forests with mountain ash and gum trees. The cold tropical rainforests in the Melbourne area were spectacular. Marsupials include: koalas, opossums, platypus, flying foxes,and lyre birds.
Savanna: this is typically, a grassland or woodland area. Inhabitants include: emus, red kangaroos, rabbit bandicoots, and parrots.
Desert: this area is typically barren of vegetation and desert varieties of eucalptyus and acacia. Animals living here include: the marsupial moles, devil lizards, and parakeets. Notice that the desert barrier of the interior of Australia isolate the four corners of Australia.