The rocky shore is an outstanding example of an environmental gradient (”wet-dry”; “salt waterfresh water”; ”stable-dynamic”-gradient). The biocoenoses on it usually present themselves in the form of different zones perpendicular to this gradient. Several schemes for this zonation have been proposed in the past, most recently one by Van Loenhoud & Van de Sande (1977). In their scheme, three major units of the zonation are distinguished: The sublittoral region, the littoral region, and the maritime region. The littoral region, constituting the actual border zone between the sea and the land, is divided into infralittoral margin, the lower eulittoral, the upper eulittoral, and the supralittoral margin.