the scheme used to find out these ecoregions is more or less the same as that for terrestrial ecoregions. major habitat types are identified: polar, temperate shelfs and seas, temperate upwelling, tropical upwelling, tropical coral, pelagic, abyssal, and hadal (ocean trench) — which correspond to the terrestrial biomes. major biogeographic realms, analogous to the seven terrestrial ecozones, represent large regions of the ocean basins: north temperate atlantic, eastern tropical atlantic, western tropical atlantic, south temperate atlantic, north temperate indo-pacific, central indo-pacific, eastern indo-pacific, western indo-pacific, south temperate indo-pacific, southern ocean, antarctic, arctic, and mediterranean.