Did you know there’s a hidden world of animals whose names start with O? From the seas to the skies, 96 creatures begin their expedition with this round letter.
Why should you care? These animals might be the missing piece in your natural knowledge or the star of your next trivia night.
Imagine spotting an odd bird or naming an unusual pet, starting with O. This list will open your eyes to animals you may have never heard of.
Ready to meet furry friends, scaly swimmers, and feathered flyers that all share the same first letter? We’ll take you on a tour of 96 incredible O-animals, from the common to the rare.
You’ll have a new set of creatures to discuss by the end. Let’s start our O-animal adventure!
A Compilation of 96 Animals That Begin With The Letter O
1. Ocean Sunfish
A large, flat-bodied fish with rough skin and no tail fin, using its dorsal and anal fins for movement. It can grow up to 3 meters in length.
- Region of Habitat: Tropical and temperate oceans worldwide
- Scientific Name: Mola mola
- Place of Origin: Global oceanic waters
- Feeding Habits: Jellyfish, small fish, plankton, squid
- What Sound They Make: Silent, no audible sound
Fun Facts: Ocean sunfish can weigh over 2,000 kilograms, making them one of the heaviest fish. They are known for basking at the surface and diving deep for food.
2. Oceanic Whitetip Shark
A large, predatory shark with distinctive white-tipped fins and a robust body, growing up to 3.9 meters. It is a strong swimmer known for its long pectoral fins.
- Region of Habitat: Open tropical and warm temperate seas
- Scientific Name: Carcharhinus longimanus
- Place of Origin: Global tropical and subtropical waters
- Feeding Habits: Fish, squid, seabirds, carrion
- What Sound They Make: Silent, no audible sound
Fun Facts: The Oceanic Whitetip is considered one of the most aggressive sharks, often following ships and scavenging for food. Its white-tipped fins make it easily recognizable.
3. Ocelot
A medium-sized, sleek, wild cat with golden-yellow fur covered in black spots and stripes, it reaches about 1 meter in length and weighs around 16 kilograms.
- Region of Habitat: Tropical and subtropical forests
- Scientific Name: Leopardus pardalis
- Place of Origin: Central and South America
- Feeding Habits: Small mammals, birds, reptiles
- What Sound They Make: Growls, meows, purrs
Fun Facts: Ocelots are nocturnal hunters and are excellent swimmers and climbers. Their beautiful spotted fur has made them targets for illegal poaching, leading to conservation efforts to protect them.
4. Ochre-bellied Flycatcher
A small bird with a vibrant ochre-colored belly, greenish upper body, and short, slender beak. It grows up to 13 centimeters in length and weighs about 10 grams.
- Region of Habitat: Tropical forests of Central and South America
- Scientific Name: Mionectes oleagineus
- Place of Origin: Central and South America
- Feeding Habits: Insects, fruits
- What Sound They Make: High-pitched trills and calls
Fun Facts: Ochre-bellied Flycatchers are known for their acrobatic flying skills as they hunt insects mid-air. They often hover while feeding, which sometimes gives them a hummingbird-like appearance.
5. Octopus
A soft-bodied marine animal with eight arms, a bulbous head, and the ability to change colors to blend with its surroundings. They can grow up to 4.3 meters in length.
- Region of Habitat: Oceans worldwide, mostly coastal regions
- Scientific Name: Octopoda
- Place of Origin: Global ocean waters
- Feeding Habits: Crabs, fish, mollusks
- What Sound They Make: Silent, no vocal sounds
Fun Facts: Octopuses are highly intelligent and can escape from enclosures, open jars, and use tools. They also squirt ink as a defense mechanism to confuse predators while they escape.
6. Oilbird
A medium-sized, nocturnal bird with a brown body and white spots, it has large eyes adapted for night vision and can grow up to 49 centimeters in length.
- Region of Habitat: Northern South America
- Scientific Name: Steatornis caripensis
- Place of Origin: Northern South America
- Feeding Habits: Fruit, especially oil palm and laurel trees
- What Sound They Make: Loud clicking and screeching sounds
Fun Facts: Like bats, oilbirds guide in complete darkness using echolocation. They are named for their oily flesh, once harvested for oil. They are the only fruit-eating nocturnal bird in the world.
7. Okapi
A forest-dwelling mammal with a body resembling a horse but with zebra-like striped legs. It can grow up to 2.5 meters long and weighs around 250 kilograms.
- Region of Habitat: Dense rainforests of Central Africa
- Scientific Name: Okapia johnstoni
- Place of Origin: Central Africa
- Feeding Habits: Leaves, fruits, fungi
- What Sound They Make: Low-frequency sounds, inaudible to humans
Fun Facts: The okapi is closely related to the giraffe and is often called the “forest giraffe.” Its long tongue helps it grab leaves and clean its eyes and ears!
8. Olingo
A small, tree-dwelling mammal with a slender body, thick brownish fur, and a long bushy tail. It typically measures around 42 centimeters in body length and weighs up to 2 kilograms.
- Region of Habitat: Central and South American tropical forests
- Scientific Name: Bassaricyon
- Place of Origin: Central and South America
- Feeding Habits: Fruits, small insects
- What Sound They Make: Whistles, chatters, and occasional growls
Fun Facts: Olingos are nocturnal animals often mistaken for kinkajous, their close relatives. They are very deft climbers and spend most of their time in trees, foraging for fruits.
9. Olive Baboon
A large, ground-dwelling monkey with olive-gray fur, strong limbs, and a dog-like face. It can reach up to 70 centimeters and weigh around 37 kilograms.
- Region of Habitat: Sub-Saharan Africa
- Scientific Name: Papio anubis
- Place of Origin: Africa
- Feeding Habits: Omnivorous, eating fruits, insects, small mammals
- What Sound They Make: Grunts, barks, and screeches
Fun Facts: Olive baboons are highly social animals, living in large troops of up to 150 members. They are known for their complex social structure, grooming behaviors, and strength of group bonds.
10. Olive Ridley Turtle
A small to medium-sized sea turtle with a heart-shaped, olive-green shell. It can grow up to 70 centimeters in length and weigh around 45 kilograms.
- Region of Habitat: Tropical oceans worldwide
- Scientific Name: Lepidochelys olivacea
- Place of Origin: Global tropical waters
- Feeding Habits: Jellyfish, crabs, shrimp
- What Sound They Make: Silent, no vocalizations
Fun Facts: Olive Ridley Turtles are the most abundant sea turtle species and are famous for their synchronized nesting, called “arribada,” where thousands of females come ashore at once to lay eggs.
11. Olm
A blind, cave-dwelling amphibian with pale, translucent skin and elongated, eel-like bodies. It can grow up to 30 centimeters in length and is entirely aquatic.
- Region of Habitat: Caves in Central and Southeastern Europe
- Scientific Name: Proteus anguinus
- Place of Origin: Europe
- Feeding Habits: Small aquatic invertebrates
- What Sound They Make: Silent
Fun Facts: Olms are unique for their long lifespan, up to 100 years. Because of their pinkish skin, they are often called “human fish” and can survive without food for years in caves.
12. Ommatokoita
A parasitic copepod that attaches itself to the eyes of sharks, especially the Greenland shark. It is very small, measuring just a few millimeters in length.
- Region of Habitat: Arctic waters
- Scientific Name: Ommatokoita elongata
- Place of Origin: Arctic regions
- Feeding Habits: Parasitic, feeds on shark tissue
- What Sound They Make: Silent
Fun Facts: Ommatokoita can cause partial blindness in sharks by attaching to their corneas. Despite this, the sharks are unaffected in their hunting due to their reliance on other senses for navigation.
13. Onager
A wild ass with a pale brown coat and a dark stripe down its back. It can grow up to 2.5 meters long and weighs around 250 kilograms.
- Region of Habitat: Deserts and steppes of Asia
- Scientific Name: Equus hemionus
- Place of Origin: Central Asia
- Feeding Habits: Grasses, shrubs, leaves
- What Sound They Make: Brays
Fun Facts: Onagers are known for their speed, reaching up to 70 kilometers per hour. They are critically endangered due to habitat loss and competition with livestock for grazing areas.
14. Opah
A large, deep-bodied fish with strikingly round, silvery bodies and bright red fins. It can grow up to 2 meters long and weigh around 270 kilograms.
- Region of Habitat: Deep tropical and temperate ocean waters
- Scientific Name: Lampris guttatus
- Place of Origin: Global oceanic waters
- Feeding Habits: Squid, krill, small fish
- What Sound They Make: Silent
Fun Facts: Opah is unique for being the only fully warm-blooded fish, which allows it to regulate its body temperature and thrive in colder waters where other fish may not survive.
15. Opossum
A small, marsupial mammal with grayish fur, a pointed face, and a long, prehensile tail. It can grow up to 50 centimeters in length and weighs around 5 kilograms.
- Region of Habitat: North and South America
- Scientific Name: Didelphis
- Place of Origin: Americas
- Feeding Habits: Omnivorous, eating fruits, insects, small animals
- What Sound They Make: Hissing, growling
Fun Facts: Opossums are well known for their “playing dead” defense mechanism, which causes them to fall over and emit a foul odor when threatened. They are also the only marsupial found in North America.
16. Orange Roughy
A deep-sea fish with a reddish-orange body, rough skin, and large eyes. It grows up to 75 centimeters in length and can weigh up to 7 kilograms.
- Region of Habitat: Deep ocean waters worldwide
- Scientific Name: Hoplostethus atlanticus
- Place of Origin: Deep ocean, especially around New Zealand
- Feeding Habits: Small fish, squid, crustaceans
- What Sound They Make: Silent
Fun Facts: Orange roughy can live up to 150 years, making them one of the longest-living fish species. Their slow growth and late maturity make them vulnerable to overfishing.
17. Orange-bellied Parrot
A small, brightly colored parrot with green plumage and a vibrant orange belly. It grows up to 20 centimeters in length and weighs around 50 grams.
- Region of Habitat: Coastal areas of southern Australia
- Scientific Name: Neophema chrysogaster
- Place of Origin: Australia
- Feeding Habits: Seeds, fruits, flowers
- What Sound They Make: High-pitched chirps
Fun Facts: The orange-bellied parrot is critically endangered, with only a few individuals left in the wild. Conservation efforts are ongoing to save this colorful parrot from extinction.
18. Orangethroat Darter
A small freshwater fish with a vibrant orange throat and body patterns of blue and green. It grows up to 6 centimeters in length.
- Region of Habitat: Freshwater streams in North America
- Scientific Name: Etheostoma spectabile
- Place of Origin: North America
- Feeding Habits: Insects, small invertebrates
- What Sound They Make: Silent
Fun Facts: Orangethroat darters are known for their bright colors during the breeding season, with males becoming especially vibrant to attract mates. They thrive in clear, fast-flowing streams.
19. Orangutan
Large, tree-dwelling primates with long reddish-brown hair, long arms, and highly intelligent expressions. They can grow up to 1.5 meters tall and weigh around 90 kilograms.
- Region of Habitat: Tropical rainforests in Southeast Asia
- Scientific Name: Pongo
- Place of Origin: Borneo and Sumatra
- Feeding Habits: Fruits, leaves, bark, insects
- What Sound They Make: Long calls, grunts
Fun Facts: Orangutans are known for their remarkable use of tools and ability to learn new behaviors. They spend most of their lives in trees and build nests to sleep in every night.
20. Orb Weaver Spider
Medium-sized spiders with rounded abdomens, colorful patterns, and long legs. They can grow up to 4 centimeters in length.
- Region of Habitat: Worldwide, in gardens, forests, and fields
- Scientific Name: Araneidae
- Place of Origin: Global
- Feeding Habits: Insects
- What Sound They Make: Silent
Fun Facts: Orb weaver spiders are famous for their intricate circular webs, which they spin to catch flying insects. Their webs are often rebuilt daily, and the silk they produce is incredibly strong.
21. Orca (Killer Whale)
Large marine mammals with black-and-white coloring, reaching up to 8 meters long and weighing up to 6 tons.
- Region of Habitat: Oceans worldwide, especially colder waters
- Scientific Name: Orcinus orca
- Place of Origin: Global
- Feeding Habits: Fish, seals, whales
- What Sound They Make: Clicks, whistles, pulsed calls
Fun Facts: Orcas are highly social animals that live in family groups called pods. They use echolocation to hunt and are known for their coordinated hunting techniques, often working together to capture prey.
22. Oribi
A small, graceful antelope with a slender build, light brown fur, and short, straight horns. They grow up to 92 centimeters tall and weigh around 20 kilograms.
- Region of Habitat: Grasslands and savannas in Africa
- Scientific Name: Ourebia ourebi
- Place of Origin: Africa
- Feeding Habits: Grass, leaves, herbs
- What Sound They Make: Whistles, bleats
Fun Facts: Oribis are excellent jumpers and can leap several feet into the air to escape predators. They live in small groups and are very territorial, marking their areas with scent from glands near their eyes.
23. Orthacanthus
An extinct, eel-like shark with long, slender bodies and a dorsal fin running the length of its back. They could grow up to 3 meters in length.
- Region of Habitat: Ancient freshwater swamps and rivers
- Scientific Name: Orthacanthus
- Place of Origin: Prehistoric waters
- Feeding Habits: Fish, smaller aquatic creatures
- What Sound They Make: Silent
Fun Facts: Orthacanthus had a unique appearance, with a spine extending from its head and a long dorsal fin, giving it an almost serpent-like look. Fossils suggest they were top predators in their freshwater ecosystems.
24. Ortolan Bunting
A small songbird with olive-green plumage, yellow underparts, and a short, stout beak. It grows up to 16 centimeters in length and weighs around 20 grams.
- Region of Habitat: Europe and western Asia
- Scientific Name: Emberiza hortulana
- Place of Origin: Europe and Asia
- Feeding Habits: Seeds, insects
- What Sound They Make: Melodic trills
Fun Facts: The Ortolan Bunting is known for its melodious song and migratory behavior. Sadly, it has also been hunted in parts of Europe as an exotic dish, leading to a decline in population and calls for protection.
25. Oryctes Rhinoceros (Rhinoceros Beetle)
Large, powerful beetles with a horn-like structure on their heads, typically measuring up to 6 centimeters in length.
- Region of Habitat: Tropical regions of Asia
- Scientific Name: Oryctes rhinoceros
- Place of Origin: Southeast Asia
- Feeding Habits: Plant matter, rotting wood
- What Sound They Make: Buzzing
Fun Facts: Rhinoceros beetles are some of the strongest animals on earth, capable of lifting objects to 850 times their weight. Their horn is primarily used in battles with other males during mating season.
26. Oryx
A large antelope with long, straight horns and pale gray fur with black markings. It can grow up to 1.5 meters tall and weigh around 200 kilograms.
- Region of Habitat: Deserts and dry savannas of Africa and the Arabian Peninsula
- Scientific Name: Oryx
- Place of Origin: Africa and the Middle East
- Feeding Habits: Grasses, shrubs
- What Sound They Make: Grunts
Fun Facts: Oryx can survive for long periods without drinking water, relying on moisture from the plants they eat. Their sharp horns are used for defense against predators, including lions and hyenas.
27. Osprey
A large bird of prey with a white head, dark eye stripe, and brown wings, growing up to 60 centimeters long with a wingspan of 1.8 meters.
- Region of Habitat: Near water bodies worldwide
- Scientific Name: Pandion haliaetus
- Place of Origin: Global
- Feeding Habits: Fish
- What Sound They Make: Sharp, whistling calls
Fun Facts: Ospreys are incredible hunters known for their spectacular dives into water to catch fish. Their reversible outer toes allow them to grasp slippery prey more effectively.
28. Ostracod
Tiny, shrimp-like crustaceans with a hard, bivalve-like shell, typically measuring only a few millimeters in length.
- Region of Habitat: Oceans, freshwater bodies, and even moist terrestrial environments worldwide
- Scientific Name: Ostracoda
- Place of Origin: Global
- Feeding Habits: Plankton, detritus
- What Sound They Make: Silent
Fun Facts: Ostracods are often called “seed shrimp” due to their shape. They have existed for over 500 million years, making them one of the oldest species on Earth. Some species are bioluminescent, glowing in the dark.
29. Ostrich
The world’s largest bird has long legs, a long neck, and black and white feathers. They can grow up to 2.7 meters tall and weigh around 145 kilograms.
- Region of Habitat: African savannas and deserts
- Scientific Name: Struthio camelus
- Place of Origin: Africa
- Feeding Habits: Plants, seeds, insects
- What Sound They Make: Booming calls, hissing
Fun Facts: Ostriches are flightless birds, but they are the fastest runners of any bird species, reaching up to 70 kilometers per hour.
They have the largest eyes of any land animal, which helps them spot predators from far away.
30. Otter
A sleek, semi-aquatic mammal with a long body, webbed feet, and thick fur. They can grow up to 1.2 meters in length and weigh around 11 kilograms.
- Region of Habitat: Rivers, lakes, coastal areas worldwide
- Scientific Name: Lutrinae
- Place of Origin: Global
- Feeding Habits: Fish, crustaceans, amphibians
- What Sound They Make: Squeaks, whistles, growls
Fun Facts: Otters are known for their playful behavior, often seen sliding down riverbanks and using rocks to break open shells. Their dense fur is the thickest of any animal, helping them stay warm in cold water.
31. Ovenbird
A small, migratory songbird with olive-brown upperparts, a white belly, and a distinctive orange crown. It typically grows up to 15 centimeters in length and weighs around 20 grams.
- Region of Habitat: North and Central American forests
- Scientific Name: Seiurus aurocapilla
- Place of Origin: North America
- Feeding Habits: Insects, spiders, larvae
- What Sound They Make: Repetitive, loud, teacher-like “TEACHER, TEACHER” calls.
Fun Facts: Ovenbirds are named after their unique, dome-shaped nests resembling old-fashioned ovens. They are known for their loud, distinctive songs and are commonly heard during the breeding season in forests.
32. Owl
A nocturnal bird of prey with large eyes, a rounded head, and silent flight. It can grow up to 70 centimeters in length depending on the species.
- Region of Habitat: Worldwide, in forests, deserts, and tundra
- Scientific Name: Strigiformes
- Place of Origin: Global
- Feeding Habits: Small mammals, birds, insects
- What Sound They Make: Hoots, screeches, and whinnies
Fun Facts: Owls are renowned for their exceptional night vision and ability to rotate their heads up to 270 degrees. They use their silent flight to sneak up on prey, making them expert hunters.
33. Ox
A large, domesticated bovine with a sturdy body and thick coat, typically used for agricultural work. It can grow up to 1.8 meters tall and weigh around 1,000 kilograms.
- Region of Habitat: Worldwide, domesticated
- Scientific Name: Bos taurus
- Place of Origin: Global, domesticated
- Feeding Habits: Grass, hay
- What Sound They Make: Lowing, bellowing
Fun Facts: Oxen are incredibly strong animals, often used to pull heavy loads or plow fields. Despite their size, they are docile and easy to train, making them priceless to farming communities worldwide.
34. Oxpecker
A small, brownish-gray bird with a distinctive red or yellow beak that feeds on ticks and other parasites from large mammals. It grows up to 23 centimeters in length.
- Region of Habitat: Sub-Saharan Africa
- Scientific Name: Buphagus
- Place of Origin: Africa
- Feeding Habits: Parasites, ticks, insects
- What Sound They Make: Sharp, chattering calls
Fun Facts: Oxpeckers have a symbiotic relationship with large mammals like rhinos and buffalo, cleaning them of parasites. They are also known for their loud, constant chatter while foraging on their hosts.
35. Oxyrhynchus
A small freshwater fish with a long, pointed snout, sleek body, and silver scales. It grows up to 20 centimeters in length.
- Region of Habitat: Freshwater bodies in South America
- Scientific Name: Oxyrhynchus
- Place of Origin: South America
- Feeding Habits: Small invertebrates, algae
- What Sound They Make: Silent
Fun Facts: Oxyrhynchus fish are known for their long snouts, which they use to search for food in riverbeds. Their name comes from the Greek word for “sharp snout,” and they are common in South American rivers.
36. Oystercatcher
A medium-sized shorebird with black-and-white plumage and a bright orange beak. It can grow up to 50 centimeters in length and weigh around 700 grams.
- Region of Habitat: Coastal areas worldwide
- Scientific Name: Haematopus
- Place of Origin: Global coastal regions
- Feeding Habits: Mollusks, worms, crustaceans
- What Sound They Make: Loud, piping calls
Fun Facts: Oystercatchers use their strong, pointed beaks to pry open shellfish. They are easily recognized by their striking black-and-white bodies and bright orange beaks and common sights on sandy beaches.
Some More Unique Animals That Begin With The Letter O
1. Oarfish
2. Oak Toad
3. Oceanic Squid
4. Oecomys
5. Ogcocephalus
6. Oilfish
7. Okenia
8. Old World Flycatcher
9. Olive Sea Snake
10. Olive-backed Sunbird
11. Olive-winged Bulbul
12. Omura’s Whale
13. Oncilla
14. Onion Coral
15. Onykia
16. Ophiacodon
17. Ophiocoma
18. Ophiogomphus
19. Ophisternon
20. Opossum Shrimp
21. Ornate Hawk-Eagle
22. Ornate Box Turtle
23. Ornithocheirus
24. Ornitholestes
25. Ornithomimus
26. Ornithorhynchus
27. Orthacanthus
28. Orthoptera
29. Orycteropus
30. Osbornoceros
31. Oscaecilia
32. Osgood’s Rat
33. Osmia
34. Osphronemus
35. Osteolepis
36. Ostracion
37. Otarine
38. Otodus
39. Otogomphus
40. Otostigmus
41. Ottonia
42. Ouachita Map Turtle
43. Ovenbird (warbler species)
44. Overo
45. Oxacis
46. Oxalidoblatta
47. Oxysternon
48. Ozark Hellbender
49. Ozark Salamander
50. Ozotoceros
51. Oyster Crab
52. Oystershell Scale
53. Oxynotus
54. Ozark Cavefish
55. Oviraptor
56. Oxalaia
57. Ophiuchus
58. Ophthalmosaurus
59. Otolemur
60. Otocyon
The Bottom Line
We’ve explored 96 animals that start with the letter O. From land to sea to sky, these creatures show how diverse nature can be.
Some, like owls, are well-known, while others might have been new to you. This list proves that even one letter can open up a world of interesting animals.
Remember, each of these beings plays a key role in its ecosystem, whether the swift ostrich or the tiny oyster; every O-animal has unique traits and place.
Next time you’re out in nature or watching a wildlife show, keep an eye out for these O-named animals. You might spot one or recall a fact you learned here.
Which of these 96 animals surprised you the most? Nature never stops astonishing us with its variety.
