The Pattern of Distribution of the Antarctic Fauna

The antarctic climate is unfavourable to the development of a land flora, and the true land fauna is meagre and inconspicuous, consisting of little more than a few insects and fresh water Crustacea; but the water circulation of the southern ocean allows for a rich production of phytoplankton, and we have a very abundant fauna living in or on the sea. Topographical and oceanographical conditions The Antarctic continent (figure 74) is surrounded by a belt of deep, cold ocean, generally very wide, which constitutes a rather effective barrier to shelf-living organisms, but within which the physical conditions tend to be uniform in a circumpolar direction. There are, however, certain submarine ridges which radiate from the continent and which may offer routes or stepping stones for dispersal. Thus the Scotia Arc connects South America with Graham Land and has several island groups. The Kerguelen Gaussberg Ridge (about 70° - 90° E) has fewer islands but no wider gaps of abyssal depths, and south of New Zealand the deep belt is narrower than at most other points.