Birds beginning with O
Fish beginning with O
Reptiles beginning with O
Mammals that start with O
Oaxaca giant deer mouse
Oaxacan pocket gopher
Obi island cuscus
Obi mosaic-tailed rat
Occidental gerbil
ocelot
ochre bush squirrel
ochre mole rat
Ogilby's duiker
Ogilvie mountain collared lemming
Ohiya rat
okapi
Oku mouse shrew
Olalla's titi
oldfield mouse
oldfield mouse
oldfield white-bellied rat
Olga's dormouse
olingo
olive colobus
olive grass mouse
olive montane mouse
olive-backed pocket mouse
Olivier's shrew
Olrog's chaco mouse
Olympic marmot
Omilteme cottontail
one-striped short-tailed opossum
one-toothed shrew mouse
Ontong Java flying fox
Ooldea dunnart
opossum rat
orange fruit bat
orange leaf-nosed bat
orange mouse
orange nectar bat
orange-bellied Himalayan squirrel
orange-spined hairy dwarf porcupine
orangutan
Ord's kangaroo rat
oribi
Oriente cave rat
Orinoco agouti
Orinoco sword-nosed bat
ornate flying fox
ornate shrew
Osgood's horseshoe bat
Osgood's leaf-eared mouse
Osgood's mouse
Osgood's rat
Osgood's short-tailed opossum
otter civet
Oubangui mouse
Owl's spiny rat
owl-faced monkey
Owston's palm civet
Oyapock's fish-eating rat