Here you’ll find 28 Small animals that start with O that begin with O, organized from “Oak toad” to “Oyster toadfish”. Many are amphibians, small fish, or invertebrates, with several species commonly kept as pets or seen in gardens.
Small animals that start with O are compact species whose common names begin with the letter O. Many play roles in pet keeping, education, or local ecosystems, with some notable examples like the oak toad.
Below you’ll find the table with Common name, Scientific name, Habitat, and Lifespan.
Common name: The common name helps you quickly recognize and search for a species when you need care guidance or field identification.
Scientific name: The scientific name gives exact species identification so you avoid confusion between similar common names and find precise information.
Habitat: Habitat shows where the animal typically lives, helping you understand its environmental needs or where to observe it in nature.
Lifespan: Lifespan provides usual age ranges, guiding expectations for care, study timelines, or long-term planning for pets and projects.
Small animals that start with O
| Common name | Scientific name | Habitat | Lifespan (years) | Description |
|---|---|---|---|---|
| Ocellaris clownfish | Amphiprion ocellaris | tropical coral reefs; aquarium trade | 6–10 | ≈30 g, brightly colored orange-and-white reef fish, very common aquarium pet; recognizable white bars and clown-anemone association. |
| Oscar | Astronotus ocellatus | slow-moving freshwater rivers; aquarium trade | 10–15 | ≈700 g, large cichlid popular in aquaria, intelligent and territorial; wild in South American rivers. |
| Oriental hornet | Vespa orientalis | dry open areas, near buildings | 0.5 | ≈0.5 g, distinctive red-and-yellow wasp, solitary workers live months; common wild insect near human habitations. |
| Olinguito | Bassaricyon neblina | montane cloud forests | 8 | ≈900 g, small nocturnal carnivore, newly described; arboreal and primarily wild, teddy-bear face. |
| Ord’s kangaroo rat | Dipodomys ordii | arid grassland and scrublands | 2–4 | ≈90 g, bipedal hopping rodent with large hind legs, nocturnal and wild; seed-eating cheek pouches. |
| Oriental fire-bellied toad | Bombina orientalis | temperate ponds, slow streams; pet trade | 8–12 | ≈30 g, small chunky toad with bright red belly warning color, often kept as a pet. |
| Ovenbird | Seiurus aurocapilla | temperate deciduous forest floor | 4 | ≈28 g, ground-dwelling songbird with loud, oven-like trill; migratory and common in North American forests. |
| Osprey | Pandion haliaetus | coastal waters, rivers, lakes | 15–20 | ≈1.2 kg, fish-eating raptor with reversible outer toes and white underparts; nests on poles and platforms. |
| Olive-backed sunbird | Cinnyris jugularis | tropical forest edges, gardens | 3–5 | ≈10 g, tiny nectar feeder with metallic throat in males; common wild bird often seen at flowers. |
| Orange-bellied parrot | Neophema chrysogaster | coastal saltmarshes; aviaries | 10–15 | ≈40 g, small endangered parrot with bright orange belly, kept in conservation aviaries. |
| Oak toad | Anaxyrus quercicus | pine flatwoods, scrub | 5–8 | ≈20 g, tiny toad with bumpy skin and short hops; primarily wild, secretive in leaf litter. |
| Oyster toadfish | Opsanus tau | estuaries, tidal flats | 6–10 | ≈500 g, benthic ambush predator with grating call, common in shallow US Atlantic waters; edible but small. |
| Oriental small-clawed otter | Aonyx cinereus | mangroves, freshwater streams, wetlands | 10–20 | ≈3.5 kg, smallest otter species, social and dexterous hands; kept in some zoos, otherwise wild. |
| Orange tip | Anthocharis cardamines | meadows, hedgerows, flower-rich grassland | 0.5–1 | ≈0.3 g, small butterfly with orange-tipped forewings in males; short-lived adult stage. |
| Olive-backed pipit | Anthus hodgsoni | open woodlands, grassy slopes | 2–4 | ≈18 g, slender ground-feeding songbird with streaked breast; migratory and insectivorous. |
| Oriental scops-owl | Otus sunia | woodlands, parks, gardens | 3–8 | ≈80 g, small ear-tufted owl with cryptic plumage, nocturnal and insectivorous; commonly wild near humans. |
| Ortolan bunting | Emberiza hortulana | farmland, hedgerows, scrub | 2–5 | ≈25 g, streaked brown bunting with melodic song; farmland species declining in parts of Europe. |
| Orchard oriole | Icterus spurius | riparian woodlands, orchards | 6–8 | ≈25 g, small icterid with chestnut belly in males; insectivorous and fruit-eating, common wild bird. |
| Olive thrush | Turdus olivaceus | forests, gardens in sub-Saharan Africa | 5–10 | ≈80 g, earthy olive-brown thrush with melodious song; often seen on lawns and forest edges. |
| Ocellated lizard | Timon lepidus | Mediterranean scrub, rocky areas | 6–10 | ≈300 g, large colorful lacertid with blue eye-like spots, diurnal and terrestrial; wild reptile. |
| Oriental reed warbler | Acrocephalus orientalis | reedbeds, wetlands | 2–4 | ≈25 g, plain brown warbler with strong song, migratory and insect-eating. |
| Oldfield mouse | Peromyscus polionotus | coastal dunes, grasslands | 1–2 | ≈25 g, small nocturnal rodent, sandy coloration and burrowing habit; primarily wild. |
| Orange-headed thrush | Geokichla citrina | forest understory, gardens | 5–8 | ≈60 g, striking orange head and throat, shy ground-feeder; kept occasionally in aviaries. |
| Oriental garden lizard | Calotes versicolor | gardens, scrub, urban areas | 3–5 | ≈60 g, spiny-skinned agamid lizard, territorial males show bright throat color; common wild. |
| Oriental river prawn | Macrobrachium nipponense | freshwater rivers, streams; aquaculture | 1–2 | ≈15 g, small freshwater prawn used locally for food, transparent body and long pincers. |
| Ocellated skink | Chalcides ocellatus | arid rocky areas, scrub | 4–6 | ≈20 g, smooth elongated skink with small limbs and shiny scales; secretive and wild. |
| Opaleye | Girella nigricans | rocky coastal reefs, kelp zones | 8–12 | ≈600 g, plump surfperch with opalescent eye-ring, common along Pacific coastlines. |
| Ornate tree frog | Litoria ornata | forested wetlands, Australia | 4–6 | ≈15 g, small green frog with patterned back, nocturnal and primarily wild. |
Descriptions
Ocellaris clownfish
Oscar
Oriental hornet
Olinguito
Ord’s kangaroo rat
Oriental fire-bellied toad
Ovenbird
Osprey
Olive-backed sunbird
Orange-bellied parrot
Oak toad
Oyster toadfish
Oriental small-clawed otter
Orange tip
Olive-backed pipit
Oriental scops-owl
Ortolan bunting
Orchard oriole
Olive thrush
Ocellated lizard
Oriental reed warbler
Oldfield mouse
Orange-headed thrush
Oriental garden lizard
Oriental river prawn
Ocellated skink
Opaleye
Ornate tree frog