Without phytoplankton and algae, the large marine animals would not have food to eat.

The sun-fed plankton are also important for the indigenous peoples of the Arctic who get food and clothing both from the sea (walrus, narwhals, beluga, other whales, polar bear, and fish) and the land (caribou, reindeer and musk-ox). When uneaten organisms die, they sink to the seafloor, feeding fish, seastars, soft corals, and other organisms in deeper water. The blooms of algae and phytoplankton feed zooplankton and larger predators, which are themselves in turn eaten, and so on up the food chain. This explosion of life supports the entire food web for the whole year-from soft corals on the seafloor to the arctic foxes on the ice. During this bright period, Arctic algae and phytoplankton kick into overdrive, using photosynthesis to use the 24-hour sunlight to make food. Come March, the sun rises low in the Arctic horizon, and it won't set until six months later in September. What keeps this marine ecosystem going are organisms you can't see with the naked eye: microscopic phytoplankton and ice algae. These large marine mammals, who move easily between ice, water and land, are part of the diverse fauna of the Arctic Ocean. The symbol of the Arctic is often the polar bear, the pole's cute yet fearsome top predator. In the Antarctic, the only human residents are scientists and technicians at isolated research stations whose food must be shipped in by boat. All but one or two percent of Antarctic land is covered by glaciers, some of which are more than 15,000 feet (4,700 meters) thick. Meanwhile, the southern polar region has the opposite geography, with the huge landmass of Antarctica surrounded by the turbulent Southern Ocean. On the adjacent land, communities of native peoples have thrived for thousands of years by adapting to life along the edge of the ice. Depending on the season, much or all of the Arctic Ocean is covered by a layer of sea ice, ranging in thickness from a few inches to over six feet, which is always shifting as it floats on the ocean's surface. In the northern polar region, the water and ice of the Arctic Ocean are surrounded by land. The environments at the poles are some of the harshest on Earth-yet animals have found ways to survive there against the odds.Īlthough both are icy and frigid, the poles are actually more different than you might expect.

Both the Arctic Ocean and the Southern Ocean are defined by ice and dramatic shifts between endless day and endless night. Travel to the ends of the earth-literally-and discover the polar ocean basins.

The land of blood and ice