Weird But True! Party Animals. Try This! Explore More. The narwhal's tusk can grow to nine feet three meters long. Above and Below. Please be respectful of copyright. Unauthorized use is prohibited. Harp seal A harp seal swims in the cold Arctic Ocean. Growing Season. See lots of pictures of icebergs and find out more about them. Need help? How to videos Why join? Polar habitats. What are polar habitats? Polar habitats are located in the very north and very south of the globe — the two pole ends of the Earth.
The northern polar region is called the Arctic, and in the south the polar region is the continent of Antarctica. Polar habitats have just two seasons — summer and winter but even summer is normally very cold. Polar habitats have tundra, which is ground that is nearly always frozen. Because it is too cold for trees to grow in arctic habitats, animals find other places to live such as holes in the ground, or in caves made from snow.
Most are carnivores they eat meat and hunt for fish as well as smaller animals. Animals in polar regions have adapted to survive in these extreme conditions. These areas have large mammals, such as caribou, bears, wolves and foxes, and a variety of plants.
In summer, migratory birds and other wildlife come to the Arctic to raise their young. The size and shape of the Arctic Ocean Basins are roughly similar to those of the Antarctic continent, and is 1. It is mostly covered by pack ice frozen seawater averaging meters feet thick. People come only to visit for a short time. Apart from research stations, there are no permanent human settlements on the Antarctic continent today. The Arctic, by contrast, is diametrically different in several respects.
Here, land masses surround an ocean that is centred on the pole. In contrast to the Southern Ocean, the Arctic Ocean has a permanent sea-ice cover whose area varies with the seasons.
It achieves its greatest extent at the end of winter and its smallest size at the end of summer, whereby scientists are observing a steady decrease in the extent of summer ice.
Since the beginning of satellite measurements in , the surface area of summer ice has shrunk by around three million square kilometres. This is an area about eight times the size of Germany. Because the continents of Europe, Asia and North America extend far into the Arctic region, the Arctic has been more successfully settled by plants, animals and people than the Antarctic.
Historical evidence suggests that the first aboriginal people were hunting in the coastal regions of the Arctic Ocean 45, years ago. Today more than four million people live within the Arctic polar region. Where does the Arctic begin, where the Antarctic? Seamen at that time used the constellations of the northern sky, primarily Ursa Major and Ursa Minor, to aid them with orientation during their voyages of discovery.
The two circles mark the geographic latitudes at which the sun does not set on the dates of the respective summer solstices. In the northern hemisphere the summer solstice usually falls on the 21st of June and in the southern hemisphere it is usually the 21st or 22nd of December.
They are currently moving toward the geographic poles by around The Arctic Circle has never become established, however, as the definitive southern boundary of the Arctic region.
North of this imaginary line the long-term average temperature for the month of July lies below ten degrees Celsius. By this criterion the Arctic Ocean, Greenland, Svalbard, large parts of Iceland, and the northern coasts and islands of Russia, Canada and Alaska all belong to the Arctic realm.
In Siberia and North America, on the other hand, cold Arctic air pushes the temperature boundary further to the south, so that regions such as the northeastern part of Labrador, the Hudson Bay, and a large portion of the Bering Sea are included as part of the Arctic 1. On the Arctic Circle it does not set for 24 hours, and on the Antarctic Circle it does not rise for 24 hours.
Another natural southern boundary sometimes used for the northern polar region is the Arctic tree line. As the name suggests, the present-day climate conditions north of this line are so harsh that trees are no longer able to survive. In North America, for example, this transition zone is a relatively narrow strip. In northern Europe and Asia, however, it can be up to kilometres wide.
In some areas, however, it can be located as much as kilometres to the south of the temperature boundary. According to this definition, western Alaska and the Aleutians would also belong to the Arctic, and the Arctic region would have a total area of around 20 million square kilometres.
A third natural boundary can be delineated based on ocean currents. According to this definition, the Arctic waters begin at the point where cold, relatively low-saline surface-water masses from the Arctic Ocean meet warmer more saline waters from the Atlantic or Pacific Ocean at the sea surface.
In the area of the Canadian Arctic Archipelago, the island group between North America and Greenland, this convergence zone extends to 63 degrees north latitude. As it continues eastward, it turns to the north between Baffin Island and Greenland.
In the Fram Strait, the marine area between East Greenland and Svalbard, it is located as far as 80 degrees north, i. On the other side of the Arctic Ocean, in the Bering Sea, the definition of a convergence zone is somewhat more difficult, because here the water masses from the Pacific and Arctic Oceans mix extensively with each other instead of one flowing over the other.
On maps, therefore, this vague boundary line runs straight across the narrow Bering Strait. Besides these three boundaries to the Arctic, which are all characterized by natural features, other boundaries have been defined according to different delineating criteria.
On the North American continent they draw the line at 60 degrees latitude. The most generous definition of the Arctic is found in the Arctic Human Development Report AHDR , where political and statistical aspects were considered in defining the area, which is why the boundary, especially in Siberia, extends further to the south than any other. If, in special cases, other definitions of the Arctic region are necessary, this will be specifically pointed out. In the southern hemisphere, the definition of the boundary is not as difficult.
The fact that the continent of Antarctica is essentially an island and the presence of distinctive ocean currents allow a relatively clear delineation of the boundary of the southern polar region.
This is the encircling oceanic zone where cold, northward-flowing surface water from the Antarctic meets warmer southward-flowing water masses from the north. The cold, saline water sinks as a result of the density differences, and is diverted beneath the warmer water masses. The precise position of the convergence zone, however, varies somewhat depending on longitude, the weather and time of year, and can therefore shift regionally by as much as kilometres to the north or south.
This World Ocean Review will conform to the delineation of the Antarctic polar region established in by the Antarctic Treaty unless otherwise noted. Wandering continents The fact that both polar regions of the Earth are covered with ice at the same time is an exceptional situation in the 4. The German polar researcher Alfred Wegener was the first to scientifically postulate that the continents are moving.
According to his theory the outer shell of the Earth, the crust, with a thickness of up to 60 kilometres, broke apart into large plates around three to four billion years ago. The plates travel at speeds up to ten centimetres per year. In this way, new continental or ocean crust is formed at the fractures.
Climate researchers consider continental drift to be one of the most influential factors in the history of ice formation in the polar regions.
After all, the relative positions of the continents and oceans determine the patterns of air and ocean currents, and thus the distribution of heat on the planet. In the past, parts of both regions have been located in the opposite hemispheres.
Antarctica — an ancient continent In order to understand the origins of the southern polar region, it is necessary to know that the Antarctic continent actually consists of two parts: One is the relatively large, solid landmass of East Antarctica, which is composed of continental crust up to 3.
The other is West Antarctica, which comprises four considerably smaller and thinner crustal blocks.
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