Australia has many unique plants and animals due to its long isolation from other continents. 70% of Australia's flora and fauna are endemic, including well known marsupials like kangaroos and koalas which carry their young in pouches. Australia is also home to unusual egg-laying mammals such as platypuses and echidnas, the flightless emu, and dangerous reptiles including crocodiles, snakes, and spiders. Many of Australia's over 24,000 native plant species are found nowhere else, such as bottle brush, wattle, and eucalyptus trees.