• (1) O - Obiknovenÿ osetr
• (2) Obiknoven? osetr - Occasional-shrimp goby
• (3) Occelated Turkey - ocellated tonguefish
• (4) Ocellated Tonguefish - Ogaq
• (5) Ogar - Ojiblanco De Pemba
• (6) Ojigrande - Okpo
• (7) Okpo - Oliivitimali
• (8) Oliivitoka - Olivrücken-Bartvogel
• (9) Olivrücken-Baumspäher - Onaga-ei
• (10) Onaga-hanadai - Oohibarichidori
• (11) Oohigenashiyotaka - Oral-Rim Mealybug
• (12) Orali - Orange-eared Tanager
• (13) Orange-eared Tanager - Orangerote Weizengallmücke
• (14) Orangeroter Tigerbuntbarsch - Oreneta
• (15) Oreneta - Orinoco sailfin catfish
• (16) Orinoco Saltator - Orpheusbülbül
• (17) Orpheusdickkopf - Osprey
• (18) Osprey - Ostroun sametový dlouhonosý
• (19) Ostroun sametový krátkonosý - Oulouwi
• (20) Oulouwi - Oxalis White Fly
• (21) Oxapampa Poison Frog - O`ahu `Elepaio