Big. Blue. Beautiful.
These patterns are called ecoregions.
WWF defines an ecoregion as:
a large unit of land or water containing a geographically distinct assemblage of species, natural communities, and environmental conditions
The boundaries of an ecoregion are not fixed and sharp, but rather encompass an area within which important ecological and evolutionary processes most strongly interact.
The Global Ecoregions recognize the fact that, whilst tropical forests and coral reefs harbour the most biodiversity and are the traditional targets of conservation organizations, unique manifestations of nature are found in temperate and boreal regions, in deserts and mountain chains, which occur nowhere else on Earth and which risk being lost forever if they are not conserved.