Gorillas constitute the eponymous genus Gorilla, the largest extant genus of primates by physical size. They are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Africa. The genus is divided into two species: the eastern gorillas and the western gorillas, and either four or five subspecies. Gorillas’ natural habitats cover tropical or subtropical forests in Africa. Although their range covers a small percentage of Africa, gorillas cover a wide range of elevations. The mountain gorilla inhabits the Albertine Rift montane cloud forests of the Virunga Volcanoes, ranging in altitude from 2,200–4,300 meters (7,200–14,100 ft). Lowland gorillas live in dense forests and lowland swamps and marshes as low as sea level, with western lowland gorillas living in Central West African countries and eastern lowland gorillas living in the Democratic Republic of the Congo near its border with Rwanda.