As a 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 thickets, Madagascar succulent woodlands, and Madagascar mangroves.