As the coldest biome on the planet, the tundra has temperatures as cold as negative 50 degrees Fahrenheit with 24-hour nights during much of the winter. During the summer, which lasts only a few months, the temperature creeps up to 50 degrees Fahrenheit with 24 hours of daylight. Tundra is either Arctic tundra or alpine tundra. The latter lies on the uppermost reaches of mountains.
Because the Arctic tundra is cold for such a long period of time, the ground 6 inches below the top of the soil remains frozen for the entire year. A few small plants can survive in this soil, called permafrost, such as shrubs, lichens and mosses on which animals feed, but the growing season lasts only 50 to 60 days a year. Many animals can survive as well on the tundra, including polar bears, foxes, wolves, caribou and hares. Polar bears feed largely on seals and whales, while wolves and foxes need lemmings, hares and caribou to survive.
The alpine tundra has a longer growing season then its cousin in the north at 180 days, but the plants living in it are limited to dwarf trees and shrubs, tussock grasses and heaths. The animals are few as well but range from pikas, mountain goats and elk to birds and insects.