Animals That Start with O: Everything You Need To Know!

Animals That Start with O

If you love animals and are an avid animal lover, then you know that there are countless species of animals out there. So we are on a mission to list animals alphabetically, and so today, our mission is simple. 

Today we are listing animals that start with O. From the sky to underwater, from deserts to forests, we are covering them all! So, let’s get started. 

List of Animals That Start With O by Classes

A number of interesting animals’ name starts with the letter O. Our list of animals that start with o includes mammals, birds, reptiles, amphibians, fishes, and invertebrates.

Mammals That Start With Letter O

Birds That Start With Letter O

Reptiles That Start With Letter O

Amphibians That Start With Letter O

Fish that Start with O

Ocean Perch
Ocean Pout
Ocean Whitefish
Orange Chromide

Insects and Invertebrates Beginning with O

List of Animals That Start With O: Classification, Behavior, and Facts

Now comes the in-depth discussion about animals that start with o. 

1. Opossum

Wild opossum in winter weather

Scientific name: Didelphis virginiana

Type of animal: Mammal

Phylum: Chordata

Average lifespan: 2-7 years

Habitat: Opossums dwell mainly on trees. They prefer trees or areas that are close to water sources. 

Diet: Opossum is omnivorous. They feed mostly on fruits and insects. Occasionally they go for little animals like frogs. 

Fun Fact: Opossums act like they are dead when predators attack them.

Scavengers like opossums frequently visit human communities in search of food by rummaging through trash cans, garbage cans, and other storage facilities. They frequent areas with a lot of carrion, including the edges of roads, and are easy to see. Opossums also eat fruit, nuts, and grass. They are not picky eaters and will devour anything from mice and birds to insects, bugs, snakes, and even hens. 

2. Oyster


Scientific name: Ostreidae

Type of animal: Bivalve mollusks

Phylum: Mollusca 

Average lifespan: 20 years

Habitat: Oysters are mainly found on rocky shores. Large oyster beds are found in gulf areas. 

Diet: Oysters are omnivorous. They strain food particles from water. Primarily they feed on algae.

Fun Fact: Oysters do not have brains or spinal cords, meaning their nervous system is missing. So they are unable to feel pain.

Oysters, like other bivalves, typically display only one sex; however, hermaphroditism has been documented. Summer is oyster breeding season. Some species’ eggs are fertilized outside the female, whereas others do so while the female is still in the water. Oysters suitable for human consumption can be harvested after a period of 3 to 5 years.

3. Ox


Scientific name: Bos taurus

Type of animal: Mammal

Phylum: Chordata

Average lifespan:  18-22 years 

Habitat: While wild oxen live in the jungle, oxen are mainly domestic animals. The majority of them live in human-provided habitats.  

Diet: Oxen are herbivores. They live on grasses and grains. 

Fun Fact: Contrary to popular belief, oxen are actually not dumb! They are smart animals and help farmers in farming. 

The ox, sometimes known as a bullock, serves as a work animal in many contexts, including plowing, transport, and powering mechanisms that break and grind grain and create irrigation. Typically, they will be assigned to a task as a pair. More pairs are included as required by the work at hand. It is possible to have more than ten oxen in a team.

4. Octopus

An Octopus in Ocean

Scientific name: Octopus vulgaris

Type of animal: Marine mollusk

Phylum: Mollusca

Average lifespan: 6 months- 5 years

Habitat: Octopuses are found in oceans worldwide. They like warm weather, such as tropical water. 

Diet: Octopuses are omnivorous. They eat snails, crabs, small fish, etc. 

Fun Fact: Octopuses are brainy! They are also problem solvers. They can find their way through puzzles,  remember things, make predictions, use tools, and take things apart, from a crab to a lock.

Octopuses are solitary animals who excel at hiding in plain sight. Because they are all muscle and have no skeleton, they can squeeze through narrow openings. The octopus has the ability to alter its skin’s color and pattern. It is because of a special type of cell called a chromatophore. They are thought to be highly intelligent beings who can learn, manipulate tools, and recall specific locations.

5. Otter

Otter laying on grass

Scientific name: Lutra canadensis

Type of animal: Mammal

Phylum: Chordata

Average lifespan: 8-20 years

Habitat: Otters live in marine areas, lake streams, and river banks.

Diet: Otters are carnivorous. Their favorite food is small fish. They also eat frogs, crabs, sea urchins, and even turtles! 

Fun Fact: Sea otters are heavy eaters. Their daily food intake averages about a quarter of their total weight.

River otters can quickly cross land to get from one body of water to another. They favor shortcuts and frequently create popular trails as a result. They are continually looking for food while swimming, and they use features like obstacles and deepwater pools to do so. Otters find sanctuary from the elements in caves, cracks in rocks, beaver lodges, root chambers, and even dense undergrowth along the beach. 

6. Orangutan

An Orangutan walking in a forest

Scientific name: Pongo pygmaeus

Type of animal: Mammal

Phylum: Chordata 

Average lifespan: 30-40 years

Habitat: Jungle and forest areas.

Diet: Orangutans are omnivorous. They feed on fruits, insects, tree bark, etc. 

Fun Fact: Orangutans’ arms are abnormally long! They can reach a length of 2.2 meters with their arms only.

The orangutan spends the vast majority of its time in the canopy of a forest. As a result, it has developed a number of unique adaptations to help it survive in this environment. An orangutan swings from branch to branch until it is close enough to grip the next one with its long arms.

7. Ostrich

Ostrich walking on gray field

Scientific name: Struthio camelus

Type of animal: Bird

Phylum: Chordata 

Average lifespan: 40-70 years. 

Habitat: Ostrich lives in desert areas. They are also seen in Savannah. 

Diet: They are omnivores. They like eating grass. They also eat the roots of the plants and insects. 

Fun Fact: Ostrich cannot fly. But they can run really fast. They are among the fastest-running birds in the world!

There are usually fewer than a dozen ostriches in a herd. These flocks are kept in order by dominant males who also mate with the head hen. Sometimes the male mates with another member of the flock, and occasionally the male may stray and mate with a weaker hen. The dominating hen’s nest becomes the focal point of the group, with all the hens’ eggs being laid there. 

8. Orca


Scientific name: Orcinus orca

Type of animal: Mammal

Phylum: Chordata

Average lifespan: 30-50 years

Habitat: Orcas are found in every ocean on Earth.

Diet: Killer whales are carnivorous. They eat everything from fish to seabirds to seals to marine mammals to cephalopods. 

Fun Fact: Though Orcas are known as Killer Whales, they are not actually whales. They belong to the dolphin family. 

When hunting, orcas travel in pods of a maximum of 40 members. It appears that there are two types of orca pods, those that stay put and those that travel around. Different groups hunt distinct species and apply different methods of capturing their prey. All pods engage in coordinated, successful hunting strategies that have been compared to the tactics of wolf packs. 

9. Ocelot


Scientific name: Leopardus pardalis

Type of animal: Mammal

Phylum: Chordata 

Average lifespan: 8-12 years

Habitat: Ocelots prefer densely covered areas. They are found in rainforests, mangrove forests, coastal areas, and tropical forests.

Diet: Ocelots are omnivore. Their favorite meals are deer, lizards, and rodents. 

Fun Fact: Ocelots are known as Dwarf Leopards. Like fingerprints for humans, ocelot coats also have unique prints. 

Ocelots are critically endangered in Texas and elsewhere because of human persecution for their luxurious fur. The US and many other countries have laws in place to safeguard ocelots. Female ocelots often have a litter of two to three kittens that are all dark in color. Females den up for the winter in the north, although the breeding season in the tropics may be more fluid.

10. Okapi


Scientific name: Okapia johnstoni

Type of animal: Mammal

Phylum: Chordata 

Average lifespan: 15-20 years

Habitat: Okapis live in forests. They prefer dense covers such as rainforests.

Diet: They are herbivores. They eat fruits, leaves, and shoots of the trees.  

Fun Fact: Okapis live only in Congo. They are members of the giraffe family. 

Mother okapis talk to their young via infrasounds, which are too low for humans to hear. When a female okapi senses danger to her young, she will pound the ground with her hooves. A calf is left to fend for itself once it reaches the age of six months.

11. Old English Sheepdog

Old English Sheepdog

Scientific name: Canis lupus

Type of animal: Mammal

Phylum: Chordata 

Average lifespan: 12 years 

Habitat: They are pets. They live with humans and breed in captivity. 

Diet: They are omnivores. They eat everything regular dogs eat, like meat, vegetables, milk, etc. 

Fun Fact: Old English Sheepdogs have unique coats. The furry coats of the dogs have made them famous. 

This dog is a friendly, clever, and versatile breed of dog. They’re friendly with everyone in the family, and even though they’re big, they’re fine in a flat as long as they receive regular walks and playtime. Their shaggy coats don’t shed nearly as much as you’d expect, either. This breed is great for those who want a companion who is both devoted and protective of their family.

12. Oscar Fish

Oscar Fish

Scientific name: Astronotus ocellatus

Type of animal: Fish

Phylum: Chordata

Average lifespan: 10+ years

Habitat: They live in areas with freshwater and warm temperatures. 

Diet: Oscar fishes are omnivores. They eat everything from fish larvae to fish, snails, insects, etc. 

Fun Fact: There are many names for Oscar fish, but “tiger Oscars” and “marble cichlids” are the most common. 

If you own an Oscar fish, you can feed them with your own hand. They recognize their owners and trust them with hand feeding. Oscar fish are widely regarded as one of the smartest aquarium fish. But sometimes, their aggressive and territorial nature makes them difficult to care for. 

13. Owl


Scientific name: Strigiformes

Type of animal: Bird 

Phylum: Chordata 

Average lifespan: 25+ years

Habitat: Owls can live in places like deserts, plains, and mountains.

Diet: Owls are carnivores. They eat insects, rats, rodents, etc. 

Fun Fact: Owls are skilled predators. They can see prey at a distance of up to 0.5 miles.

Populations of owls tend to grow larger than those of hawks in human-inhabited places. They are somewhat safe from gunfire because they are nocturnal and act stealthily during the day. Small, competitive, insectivorous species have the highest population densities, with couples living roughly two kilometers apart inappropriate woods.

14. Oryx


Scientific name: Oryx dammah

Type of animal: Mammal

Phylum: Chordata 

Average lifespan: 15-20 years

Habitat: Oryx inhabit a wide variety of environments, including dry and semiarid lands, grasslands, rocky plains, scrub, and savannas.

Diet: Oryx are herbivores. They eat grass, fruits, and roots of shrubs. 

Fun Fact: The oryx has a reputation as a highly resilient desert animal. They can walk for up to 70 kilometers in a single night. 

An oryx is an authentic desert creature. They resemble horses in that they have a broad neck, a short mane, and a small but muscular frame. Their white cheeks and fawn-colored bodies are set off by a distinct pattern of black patterns. During rites of dominance, the dimension of their antlers and the power of their shoulders are displayed publicly.

15. Osprey Bird

Osprey Bird

Scientific name: Pandion haliaetus

Type of animal: Bird

Phylum: Chordata

Average lifespan: 9-10 years

Habitat: Osprey birds live near shallow water sources. They look for fish in the water stream. 

Diet: They are carnivores. They eat insects, fish, rodents, etc.

Fun Fact: Ospreys can survive without drinking water. They don’t need to drink water because their diet is predominantly fish.

The Osprey has no problem erecting its nest on man-made structures. Examples include structures like duck blinds, nest platforms, and channel markers. The use of these platforms has been crucial in reintroducing Ospreys to regions where they had previously gone. Nests are very always found on man-made structures in certain regions.

16. Oarfish


Scientific name: Regalecus glesne

Type of animal: Fish

Phylum: Chordata

Average lifespan: 10+ years

Habitat: They live deep inside the ocean. 

Diet: Oarfish are carnivores. They eat plankton, shrimps, squid, krill, etc.

Fun Fact: The giant oarfish is the world record holder for the longest bony fish.

If an oarfish is unwell or dying, it will float near the water’s surface. This has led many to speculate that the oarfish was the source of ancient sailors’ and beachgoers’ tales of monsters from the sea and sea serpents. Oarfish are caught for entertainment as sport fish, but commercial fishing for them is uncommon due to the fact that their gelatin flesh does not count as food.

17. Orb Weaver Spider

Orb Weaver Spider

Scientific name: Araneidae

Type of an animal: Insect

Phylum: Arthropoda

Average lifespan: 12 months

Habitat: They live everywhere around the world. They are found in trees, tall grasses, and hedges. 

Diet: Orb weaver spiders are carnivores. They eat grasshoppers, mosquitoes, ants, etc. 

Fun Fact: Many species of orb-weaving spiders eat their male offspring after mating. The females are much bigger than the males.

Orb weavers are harmless and gentle spiders that run or fall from their webs at the first hint of danger. They pose no threat to humans or domestic animals and are really beneficial because they prey on pest insects. Orb weavers are nocturnal creatures. The spider spends most of the day either sitting still on the web or leaving it altogether. 

18. Olm


Scientific name: Proteus anguinus

Type of animal: Amphibian

Phylum: Chordata 

Average lifespan: 68-100 years

Habitat: Olms live in freshwater. They prefer living inside caves. 

Diet: Olms are carnivores. They eat insects, worms, larvae, etc. 

Fun Fact: Now, Give a short description of 50-60 words of the animal based on their behavior, characteristics, and how to identify.

The olm has a serpentine body. The typical length ranges from 23 and 25 centimeters. The main part is cylindrical in shape, uniform in thickness, and divided into segments by furrows that run parallel to the myomere boundaries. The tail is narrow and short, with a flattened underside and a small fin. 

19. Otterhound


Scientific name: Canis lupus

Type of an animal: Mammal

Phylum: Chordata

Average lifespan: 5-13 years

Habitat: Ottorhounds live around humans. Mostly with their owners. 

Diet: Ottorhounds are carnivores. They eat meat, fish, milk, etc. 

Fun Fact: Otterhounds drink in an unusual manner, often with their entire noses submerged in the water while they spread the liquid out with bubbles.

Otterhounds are goofy, sociable, and affectionate family pets. They have a lot of energy that has to be released, so they adore games with their human and canine companions as well as lots of exercise. In fact, people who live in apartments will have a hard time giving their pets ample room to roam freely.

20. Ocellated Turkey

Ocellated Turkey

Scientific name: Meleagris ocellata

Type of an animal: Bird

Phylum: Chordata

Average lifespan: 4-5 years

Habitat: Ocellated turkeys are found in tropical forests. 

Diet: They are omnivorous. They eat moths, grains, seeds, beetles, etc. 

Fun Fact: The ocellated turkey hides its eggs on the ground and roosts in trees to protect its young from potential predators.

In the month of March, ocellated turkeys begin to nest. A male in full show marches past a cluster of ladies, tail outstretched and head cocked back to rest on his brushed-back feathers. His wings are trembling, and he periodically raps the ground. But when he goes to gobble, it’s much more like a farm goose trying to impersonate a turkey!  

21. Owl Butterfly

Owl Butterfly

Scientific name: Caligo

Type of the animal: Insect

Phylum: Arthropoda

Average lifespan: 133 days

Habitat: They live in dense jungle areas where they can lay eggs.

Diet: Owl butterflies are herbivores. They eat honey and nectar from flowers. 

Fun Fact: The owl butterfly gets its name from the large eyespots on its hind wings.

Owl butterflies can’t fly very far. Their range of motion is extremely limited. Because of this, birds can easily pick them off the ground. In order to avoid being seen by potential predators, they prefer to take to the air at night. Because of their resemblance to lizards and other amphibians, the eyespots also deter predators. 

22. Ornithomimus

Scientific name: Ornithomimus

Type of animal: Bird-mimic Lizard

Phylum: Chordata 

Average lifespan: 

Habitat: Ornithomimus lived in the US and part of Canada. 

Diet: Ornithomimus are carnivorous. They eat leaves, crustaceans, etc.  

Fun Fact: The name Ornithomimus comes from the Greek for “bird mimic.” They are bird-mimic dinosaurs. 

Ornithomimus had excellent vision and could spot approaching dinosaurs from great distances. Because of this, creeping up on one would be next to impossible. Large orbital fenestrae in the skull is another indicator of proportionally large eyes. This suggests that Ornithomimus had excellent eyesight, perhaps even allowing it to see in the dark.‭ 

23. Oribi


Scientific name: Ourebia ourebi

Type of animal: Mammal

Phylum: Chordata 

Average lifespan: 8-12 years

Habitat: They live in meadows, open forests, and floodplains.

Diet: Oribies are herbivores. They eat the leaves, roots, and fruits of the trees and shrubs. 

Fun Fact: Oribies hide in the undergrowth and then use their impressive vertical leaps to escape detection to survive. In times of danger, they give out high-pitched whistles.

The oribi is a species of small, fragile antelope. Its back is slightly arched, and its neck and limbs are extremely lengthy. This species is distinguished by its white underbelly, throat, chin, and rump. The exterior of the bushy tail ranges from brown to black, and the interior is white. Males are distinguished by horns that are narrow, straight, and polished at the tips. 

24. Olive Baboon

Olive Baboon

Scientific name: Papio anubis

Type of animal: Mammal

Phylum: Chordata 

Average lifespan: 25 years

Habitat: Olive baboons are found in a variety of habitats, including deserts,  grasslands, savannahs, and rainforests.

Diet: Olive baboons are omnivores. They eat roots, fruits, insects, birds, rodents, etc. 

Fun Fact: One of the most intricate social networks in the animal world is that of the olive baboon. They are great as friends. 

The Olive baboon is a huge, powerful animal. The way they walk on all fours and the long, pointed muzzles give them a canine appearance. The tails on these animals are exceptionally lengthy. A horse’s gallop can be seen in their gait. Their jaws are quite strong, and their canine teeth are exceedingly long and sharp. 

25. Oilbird


Scientific name: Steatornis caripensis

Type of animal: Bird

Phylum: Chordata

Average lifespan: 20-25 years

Habitat: The oilbird lives in mountain forests and evergreen lowlands.

Diet: The olibirds are frugivores. They eat only fruits. 

Fun Fact: Like bats, oilbirds use echolocation to navigate the dark tunnels where they rest and raise their young. 

Oilbirds are extremely social creatures that can breed in colonies of thousands of other birds. The female will then deposit between 2 and 4 eggs in a mounded nest she has constructed from the fruit she has regurgitated and her own feces. Parents feed their freshly hatched chicks various types of fruits. 
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There goes our list of animals that start with O. We are always amazed by the different kinds of animals on planet Earth. Exploring the animals whose names start with “O” has shown us a wide range of creatures. Each of the animals has its own interesting traits and ways of living. We hope this list gives you a brief and precise idea about the animals, birds, fishes, mammals, and all.

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