Arctic Alaska settlement in Arctic Alaska was driven first by discoveries of gold and later on by the extraction of petroleum. The ecosystem consists largely of tundra covering mountain ranges and coastal plains which are home to bears, wolves, sheep, oxen, reindeer, and numerous species of birds, the north coast has been defined as the Arctic coastal tundra ecoregion. Arctic Alaska is also the location of the Arctic National Wildlife Refuge, Gates of the Arctic National Park and Preserve, and the National Petroleum Reserve-Alaska. The Arctic experiences midnight sun in the summer and polar night in the winter. Arctic Alaska Arctic Alaska
Camouflage the brain to vary its opacity. By controlling chromatophores of different colours, cephalopods can rapidly change their skin patterns and colours. On a longer timescale, animals like the Arctic hare, Arctic fox, stoat, and rock ptarmigan have snow camouflage, changing their coat colour (by moulting and growing new fur or feathers) from brown or grey in the summer to white in the winter; the Arctic fox is the only species in the dog family to do so. However, Arctic hares which live in the far north of Canada, where summer is very short, remain white year-round. The principle of varying