Although most of Australia is semi-arid or desert, the continent includes a diverse range of habitats from alpine heaths to tropical rainforests. Fungi typify that diversity—an estimated 250,000 species—of which only 5% have been described—occur in Australia. Because of the continent's great age, extremely variable weather patterns, and long-term geographic isolation, much of Australia's biota is unique. About 85% of flowering plants, 84% of mammals, more than 45% of birds, and 89% of in-shore, temperate-zone fish are endemic. Australia has at least 755 species of reptile, more than any other country in the world. Besides Antarctica, Australia is the only continent that developed without feline species. Feral cats may have been introduced in the 17th century by Dutch shipwrecks, and later in the 18th century by European settlers. They are now considered a major factor in the decline and extinction of many vulnerable and endangered native species. Australia is also one of 17 megadiverse countries.