marine ecoregions
   (Biogeographic realm) Western Indo-Pacific
     18 (Biogeographic province) Red Sea and Gulf of Aden
     19 (Biogeographic province) Somali/Arabian
     20 (Biogeographic province) Western Indian Ocean
     21 (Biogeographic province) West and South Indian Shelf
     22 (Biogeographic province) Central Indian Ocean Islands
     23 (Biogeographic province) Bay of Bengal
     24 (Biogeographic province) Andaman