Bionomic principle is based on the statement that the natural complex of any rank simultaneously is an unit of biogeographical zoning of ocean. Oceanosphere is organized as set of chorological subsystems. In the most common features it is possible to speak about bioms of local (topological), regional, suboceanic and oceanic levels. Bioms of a low level consistently are included in biochores of higher rank. Physico-geographical process bears the certain ecological charge, causing spatial differentiation of a life at ocean. Natural complexes from viewpoint of the hydrobiologist are considered as areas of different items adapted to vital conditions. Any natural complex at ocean and communities of hydrobionts associated to it, represent a single unit a development of which was made by certain conditions of horizontal (latitudinal) geographical zonality, vertical stratification and was supervised by azonal (geologo-geomorphologic) factors. Three-row system of units of regional hierarchy is offered. To units of