(Sphere) [Biosphere] (Earth) - zone of life
   1.1 (Biogeographic realm) Afrotropical
   1.2 (Biogeographic realm) Australasia
   1.3 (Biogeographic realm) Indo-Malayan
   1.4 (Biogeographic realm) Neotropical
   1.5 (Biogeographic realm) Oceania
   1.6 (Biogeographic realm) Nearctic
   1.7 (Biogeographic realm) Palearctic
   2.01 (Biogeographic realm) Antarctic
   2.02 (Biogeographic realm) Arctic
   2.03 (Biogeographic realm) Mediterranean see Biogeographic province Mediterranean Sea
   2.04 (Biogeographic realm) North Temperate Atlantic
   2.05 (Biogeographic realm) North Temperate Indo-Pacific
   2.06 (Biogeographic realm) Southern Ocean
   2.07 (Biogeographic realm) South Temperate Atlantic
   2.08 (Biogeographic realm) South Temperate Indo-Pacific
   2.09 (Biogeographic realm) Central Indo-Pacific
   2.10 (Biogeographic realm) Eastern Indo-Pacific
   2.11 (Biogeographic realm) Eastern Tropical Atlantic
   2.12 (Biogeographic realm) Western Indo-Pacific
   2.13 (Biogeographic realm) Western Tropical Atlantic