Australia’s fauna is diverse, with 46 percent of its birds, 69 percent of its mammals, 94 percent of its amphibians, and 93 percent of its reptiles being native to the continent. : 4 The continent’s lengthy geographic isolation, tectonic stability, and the impact of a unique pattern of climatic change on the soil and vegetation across geological time all contribute to its high level of endemism. The relative paucity of native placental mammals is a distinguishing aspect of Australia’s wildlife. As a result, marsupials — a group of mammals that nurture their young in a pouch, including the macropods, possums, and dasyuromorphs – fill many of the ecological niches occupied by placental species elsewhere in the globe. Australia is home to two of the five known extant monotremes and several poisonous animals such as platypus, spiders, scorpions, octopus, jellyfish, mollusks, stonefish, and stingrays.