Madagascar is an island country in the Indian Ocean, approximately 400 kilometres off the coast of East Africa across the Mozambique Channel. At 592,800 square kilometres Madagascar is the world's second-largest island country, after Indonesia. The nation consists of the island of Madagascar and numerous smaller peripheral islands. Madagascar split from the Indian subcontinent around 88 million years ago, allowing native plants and animals to evolve in relative isolation. Consequently, Madagascar is a biodiversity hotspot; over 90% of its wildlife is endemic.
As the result of the island's long isolation from neighboring continents, Madagascar is home to various plants and animals found nowhere else on Earth. Approximately 90% of all plant and animal species found in Madagascar are endemic. This distinctive ecology has led some ecologists to refer to Madagascar as the 'eighth continent', and the island has been classified by Conservation International as a biodiversity hotspot. Madagascar is classed as one of 17 megadiverse countries. The country is home to seven terrestrial ecoregions: Madagascar lowland forests, Madagascar subhumid forests, Madagascar dry deciduous forests, Madagascar ericoid thickets, Madagascar spiny forests, Madagascar succulent woodlands, and Madagascar mangroves.
More than 80 percent of Madagascar's 14,883 plant species are found nowhere else in the world, including five plant families. The family Didiereaceae, composed of four genera and 11 species, is limited to the spiny forests of southwestern Madagascar. Four-fifths of the world's Pachypodium species are endemic to the island. Three-fourths of Madagascar's 860 orchid species are found here alone, as are six of the world's nine baobab species. The island is home to around 170 palm species, three times as many as on all of mainland Africa; 165 of them are endemic. Many native plant species are used as herbal remedies for a variety of afflictions. The drugs vinblastine and vincristine are vinca alkaloids, used to treat Hodgkin lymphoma, leukemia, and other cancers, were derived from the Madagascar periwinkle. The traveler's palm, known locally as ravinala and endemic to the eastern rain forests, is highly iconic of Madagascar and is featured in the national emblem as well as the Air Madagascar logo.
Like its flora, Madagascar's fauna is diverse and exhibits a high rate of endemism. Lemurs have been characterized as 'Madagascar's flagship mammal species' by Conservation International. In the absence of monkeys and other competitors, these primates have adapted to a wide range of habitats and diversified into numerous species. As of 2012, there were officially 103 species and subspecies of lemur, 39 of which were described by zoologists between 2000 and 2008. They are almost all classified as rare, vulnerable, or endangered. At least 17 species of lemur have become extinct since humans arrived on Madagascar, all of which were larger than the surviving lemur species.
A number of other mammals, including the catlike fossa, are endemic to Madagascar. Over 300 species of birds have been recorded on the island, of which over 60 percent are endemic. The few families and genera of reptiles that have reached Madagascar have diversified into more than 260 species, with over 90 percent of these being endemic, The island is home to two-thirds of the world's chameleon species, including the smallest known, and researchers have proposed that Madagascar may be the origin of all chameleons.
Endemic fish of Madagascar include two families, 15 genera and over 100 species, primarily inhabiting the island's freshwater lakes and rivers. Although invertebrates remain poorly studied in Madagascar, researchers have found high rates of endemism among the known species. All 651 species of terrestrial snail are endemic, as are a majority of the island's butterflies, scarab beetles, lacewings, spiders, and dragonflies.