Arctic Region

one of the marine zoogeographic regions. The boundary between the arctic region and the boreal region on the Atlantic side is considered to be the line running from Labrador to the southern extremity of Greenland and the western part of the Kola Peninsula. On the Pacific side, the boundary is in the area of the Bering Strait. The arctic area is divided into two subregions—the lower and the upper. The upper arctic region is characterized by an ice cover and temperatures below 0°C during most of the year and by the absence or very weak development of littoral fauna.

The fauna of the arctic region consists of approximately 3,000 species, including about 150 species of fish and 17 species of marine mammals. The most characteristic fish are the salmon family, the smelts, whitefish, certain Gadidae and flounders (Pleuronectidae), and numerous species of small benthic fish such as sea snails, armed bullheads, sculpins, and eelpouts.

Several representatives of the whales and pinnipeds are typical of the mammals. Among the pinnipeds, the Greenland seal is particularly characteristic of the lower arctic subregion, and the walrus is typical of the upper arctic sub-region. The polar bear is typical of the terrestrial predators.

Invertebrates common to the arctic region include the benthic foraminifers (more than 200 species), sponges (about 150 species), hydroid polyps and jellyfish (over 100 species), Polychaeta (about 300 species), bryozoans, (about 300 species), mollusks (about 300 species), and echinoderms (about 80 species). The lower crustaceans are represented by the copepods (about 100 species), and the higher crustaceans by the isopods and amphipods (at least 500 species). The Barents Sea and the region of the Bering Strait are exceptionally favorable for abundant breeding. The fauna of the Barents Sea is a rich food supply for the fish of the northeastern Atlantic. Enormous quantities of these fish arrive in the area in the summer and are caught by trawling. The commercial fishes are primarily the cod, haddock, ocean perch, herring, and pollock. These fishes are not found east of Novaia Zemlia; in this area the commercial fishes are salmon, whitefish, smelts, navaga, and arctic cod (of the Gadidae) and the arctic flounder (of the Pleuronectidae). In the shallows and freshened regions of the high arctic seas there is abundant brackish-water fauna, which consists basically of crustaceans and fish (salmon, whitefish, and smelts). The brackish-water fauna is a carryover from the Ice Age.

The arctic region is characterized by the absence or very slight development of a number of groups which are particularly widespread in the warmer seas. Of the single-celled animals there are radiolarians and the pelagic foraminifers; of the multicelled animals, there are the coral polyps, siphonophores, crabs, cephalopods, sea lilies, and others.