Living organisms in any biome interact through a variety of relationships. Organisms compete for food, water, and other resources. Predators hunt their prey. Some organisms coexist in mutually beneficial relationships (symbiosis), while others harm organisms for their own benefit (parasitism). Still others benefit from a relationship that neither helps nor harms the other organism (commensalism).
Animals found in the Arctic tundra include herbivorous mammals (lemmings, voles, caribou, arctic hares, and squirrels), carnivorous mammals (arctic foxes, wolves, and polar bears), fish (cod, flatfish, salmon, and trout), insects (mosquitoes, flies, moths, grasshoppers, and blackflies), and birds (ravens, snow buntings, falcons, loons, sandpipers, terns, and gulls). Reptiles and amphibians are absent because of the extremely cold temperatures. While many of the mammals have adaptations that enable them to survive the long cold winters and to breed and raise young quickly during the short summers, most birds and some mammals migrate south during the winter