High Quality Content by WIKIPEDIA articles! The fauna of Australia consists of a huge variety of animals; some 83% of mammals, 89% of reptiles, 90% of fish and insects and 93% of amphibians that inhabit the continent are endemic to Australia. This high level of endemism can be attributed to the continent`s long geographic isolation, tectonic stability, and the effects of an unusual pattern of climate change on the soil and flora over geological time. A unique feature of Australia`s fauna is the relative scarcity of native placental mammals. Consequently the marsupials—a group of mammals that raise their young in a pouch, including the macropods, possums and dasyuromorphs—occupy many of the ecological niches placental animals occupy elsewhere in the world. Australia is home to two of the 5 known extant species of monotremes and has numerous venomous species, which include the Platypus, spiders, scorpions, octopus, jellyfish, molluscs, stonefish, and stingrays. Uniquely, Australia has more venomous than non-venomous species of snakes.