The tundra's primary consumers are herbivores such as musk oxen, lemmings, caribou and arctic hares that consume grass, moss and lichen. These animals provide food for the secondary consumers, which are predators like arctic foxes and polar bears.
The two main types of tundra are arctic and alpine. Arctic tundra is the cold, dry region located above the Arctic Circle, an area surprisingly rich in plant and animal wildlife. Alpine tundra is the cold, dry part of a mountainous area above the tree line. The species of primary consumers in these areas, while still grass- and lichen-eating herbivores, vary by region.
Not all tundras have primary consumers; for example, in the limited-area Antarctic tundra, the land is inhospitable to mammals. Penguins, the land's main inhabitants, primarily eat fish.