There are two species of gorillas: the western gorilla, Gorilla gorilla, and the eastern gorilla, Gorilla beringei. The western gorilla has two subspecies: the Cross River gorilla and the western lowland gorilla. The eastern gorilla also has two subspecies, the mountain gorilla and the eastern lowland gorilla.
Gorillas, the largest living primates, are native to the forests of sub-Saharan Africa. The western lowland gorilla is the most numerous and widespread, with a range extending over much of the Congo River basin. It is the smallest of the gorillas. Its close relative, the Cross River gorilla, lives in the same area but has a somewhat different-shaped head and teeth. The eastern lowland gorilla, or Grauer's gorilla, is the largest subspecies but exists only on a range of about 4,600 square miles of tropical rainforest in the eastern Democratic Republic of the Congo. Mountain gorillas live at elevations of 8,000 to 13,000 feet in two major populations, one in the Virunda Mountains of central Africa and the other in Uganda's Bwindi Impenetrable National Park.
All gorilla subspecies are endangered or critically endangered. The primary threat to their continued existence is habitat destruction. Other threats include poaching, Ebola hemorrhagic fever and exposure to human diseases, particularly tuberculosis.