The name "Arctic" comes from the Greek word "Arktos," meaning "Bear," because the Great Bear, or Ursa Major constellation, is seen just above the North Pole. The large expanse of sea ice keeps the polar regions cool and affects the global climate. The polar sea ice is frozen seawater, while the icebergs are frozen freshwater that originates from molten glaciers on the lands surrounding the Arctic Ocean. Many of the huge icebergs in the Arctic are formed from the freshwater around Ellesmere Island in Canada.
Daylight is constant throughout the summer, while total darkness surrounds the Arctic Ocean during the winter months. The two months of sunshine result in the accumulation of a tremendous number of plant planktons as well as an increase in animals that eat them. These herbivorous animals are usually krill and other small crustaceans. While most animals leave the polar region when the sea freezes over, polar bears travel to the frozen Arctic Ocean to hunt seals during late spring or winter.