Ecologically they “are strongly cohesive units, sufficiently large to encompass ecological or life history processes for most sedentary species.”[1] The global classification system Marine Ecoregions of the World—MEOW was devised by an international team, including major conservation organizations, academic institutions and intergovernmental organizations.
[1] This system has a strong biogeographic basis, but was designed to aid in conservation activities for marine ecosystems.
Its subdivisions include both the seafloor (benthic) and shelf pelagic (neritic) biotas of each marine region.
The latter are considered analogous to the eight terrestrial realms, represent large regions of the ocean basins: Other classifications of marine ecoregions or equivalent areas have been widely developed at national and regional levels, as well as a small number of global schemes.
The WWF Global 200 work also identifies a number of major habitat types that correspond to the terrestrial biomes: polar, temperate shelves and seas, temperate upwelling, tropical upwelling, tropical coral, pelagic (trades and westerlies), abyssal, and hadal (ocean trench).