The complex Serengeti ecosystem, which spans 12,000 square miles extending from northern Tanzania into southwestern Kenya, is home to millions of animals, including 70 species of large mammals. It is a hotspot for mammal diversity—including herbivores such as wildebeest, zebra and gazelles that graze on grasses and trees, as well as lions, crocodiles, leopards and hyenas that survive by preying on the grazing herbivores.