Reading Practice 35

[1] At the far north and far south of our planet are the polar regions. The former is called the Arctic, while the latter is called Antarctica. While popular images of the polar regions sometimes confuse the two, placing – for example – polar bears alongside emperor penguins, the two regions are distinct. Of course, the fact that they are both extremely cold and, for the most part, blanketed in snow makes them look similar. However, there are key differences between the two regions which account for the differences we still see in life at the two poles.

 

[2] Geologically, the polar regions are very different. The Arctic is made up primarily of islands and deep ocean. Unlike Antarctica, therefore, the Arctic is not classified as a continent. The northern region exists at the boundary of ocean plates and – besides some older formations in Greenland – does not have a long geological history. Present-day Antarctica, on the other hand, is the product of a long geological evolution. It is a true continent (a continuous land mass) with mountain ranges reaching almost 3,800 meters. And while many of the islands of the Artic have exposed earth and vegetation for part of the year, Antarctica is almost completely glacialized. The massive ice sheet covering the continent is as thick as 2.8 miles in some places.

 

[3] Temperatures in the Arctic are more variable than at the southern pole. In part, this is because the waters surrounding the Artic islands are affected by the gulf stream’s warm waters. In contrast, Antarctica enjoys little heat circulation from other areas and is surrounded by a frigid circumpolar stream. This cold stream explains the cover of ice and the extremely low temperatures that make animal life difficult.

 

[4] Differences between life at the poles can be seen at all levels of the food chain. The first striking thing about Antarctica is that there are no terrestrial mammals, while in the north there are fox, rabbits, lemmings, reindeer, wolves, and polar bears. What accounts for this difference? Because Antarctica is covered with ice, it has virtually no vegetation beyond some lichens, while the Arctic tundra has grasses and flowering plants. What this means is that the Arctic can support small herbivorous animals, while Antarctica cannot. Moving up the food chain from these small plant-eaters, the Arctic is able to support larger carnivores. And right at the top of the food chain, we find the traditional peoples of the Arctic, including the Inuit. Antarctica, on the other hand, is the only continent to have never hosted permanent human settlements, although there are semi-permanent stations used for scientific research.

 

[5] Animal life is not restricted to land creatures, and this is where we begin to find similarities between the Arctic and Antarctic regions. Both are home to populations of seals and whales, which eat the fish and krill that grow in abundance in the oceans. The Arctic also has walrus, while Antarctica features penguins. In Antarctica, life is possible for marine creatures because they depend on food from the sea for their existence.

 

[6] All of these animals at both polar regions have developed special adaptations that enable them to endure such cold temperatures. Marine animals rely on a thick layer of fat – or blubber – that insulates them from the frigid waters in which they swim. The land animals of the Arctic require thick fur to protect themselves from cold air, and they typically have more compact body shapes and shorter appendages. The polar bear, for example, has a shorter tail and smaller ears than other bears, to prevent heat loss. There are animals in both regions – such as the penguins of Antarctica and the arctic hare – that gather together in large groups to share body heat. And of course, the white fur or undersides of both land and marine animals serves as a form of camouflage in the wintry environment.