23 Animals that Start with O

By Kevin Myers | 2023 Update

If you were wondering what animal names start with O, this article is just for you. Here is a list of 23 animals that start with the letter O.

We’ve included the most important details about these animals with a fun fact.

Enjoy reading!

1. Ox

An ox is a domesticated bovine animal typically used for draft purposes in agriculture and transportation. 

Oxen are known for their strength, endurance, and willingness to work, making them valuable assets to farmers and other rural communities in many parts of the world. 

Fun Fact: Humans have used Ox for food and work animals for over 6000 years.

2. Owl

Owls are birds of prey belonging to the order Strigiformes. They are found worldwide, from the Arctic to the tropics, and are known for their distinctive appearance, with large heads, big eyes, and hooked beaks.

Owls are well adapted to hunting at night, with excellent vision, hearing, and the ability to fly silently. 

Fun Fact: Owls have asymmetrical ears.

3. Oyster

An oyster is commonly found in saltwater environments along coastlines around the world. Oysters are known for their distinctive, elongated, pear-shaped shells, which protect their soft bodies. 

They feed by filtering water and extracting tiny plankton and other organic matter. They protect shorelines from erosion. 

Fun Fact: They can change their sex.

4. Oscar fish

It’s a popular aquarium fish known for its vibrant colouration, hardy nature, and ability to adapt to various water conditions.

Oscars are usually brightly coloured, combining orange, red, and black markings. Their intelligence and curiosity, makes them entertaining to observe in an aquarium. 

Fun Fact: You don’t want to hear this, but Oscars have teeth in their throat.

5. Orca

An orca, popularly known as a killer whale, is an enormous marine mammal that belongs to the dolphin family. 

Orcas are one of the largest species of dolphins found in oceans all over the world, from the Arctic to the Antarctic. Orcas are known for their intelligence, strength, and hunting abilities.

Fun Fact: They sleep with one eye open.

6. Old English sheepdog

They’re known for their distinctive appearance: a thick, shaggy coat covering their entire body and a rounded head with floppy ears. 

Old English Sheepdogs are large dogs that can weigh up to 60 pounds and are generally gentle, friendly, and good-natured. This makes them easy to train.

Fun Fact: The name can be debatable as these dogs are neither that ‘old’ nor ‘English’.

7. Ostrich

The ostrich is the biggest living species of bird and is native to Africa. Ostriches are flightless birds with long legs that allow them to run at high speeds. 

They can also easily cover long distances and run up to 45 miles per hour.

Fun fact: Ostriches only have two toes.

8. Otter

Otters are well-adapted to life in the water and have streamlined bodies, webbed feet, and dense, waterproof fur that helps to keep them warm and dry. 

They are known for their playful behavior and are often seen floating on their backs, using rocks to crack open shellfish, and playing with objects in the water.

Fun Fact: Some otters hold hands while sleeping.

9. Oilbird

The oilbird, also known as the guácharo, is a bird native to South America. They are the only bird species known to navigate and feed primarily by echolocation, making them similar to bats in this respect. 

In the daytime, they rest in caves in large numbers. 

Fun Fact:  The oilbird is so named because they were used to extract oil.

10. Orangutan

Orangutans are among the most intelligent of all primates. They are known for their problem-solving abilities, tool use, and complex social behaviors.

Orangutan males are mainly solitary, only coming together with females to mate. They have a slow reproductive rate and produce only one offspring every eight to ten years.

Fun Fact: We share 97% of our DNA with them!

11. Osprey

The osprey, also called the sea hawk, fish eagle, or fish hawk, is a bird of prey found on every continent except Antarctica. 

Ospreys are adapted to a life at sea and are known for their spectacular diving abilities.

They’re also widely admired for their beauty and hunting skills.

Fun Fact: Ospreys don’t need to drink water.

12. Opossum

The opossum is a species of marsupial that is native to the Americas.

They are also known for their unique defense mechanism, playing dead (known as “playing possum”), which they use to deter predators. 

Opossums have a reproductive system that is unique among mammals, with females having a marsupium (pouch) in which they raise their young

Fun Fact: Venomous snakes can’t harm Opossums.

13. Orb Weaver

The orb weaver is a type of spider known for building circular, wheel-shaped webs. These webs are typically found in gardens, forests, and other outdoor areas. 

Orb weavers are known for their ability to quickly rebuild their webs after they have been damaged or destroyed.

Fun Fact: The females are four times the size of their males.

14. Octopus

They’re known for characteristics like a soft body, multiple arms, and remarkable ability to change color and texture for camouflage and communication. 

Octopuses are highly intelligent, capable of solving problems, using tools, and exhibiting complex behaviors. They are also masters of escape, using their ability to squirt ink and their remarkable agility to evade predators.

Fun Fact: Octopuses have three hearts. 

15. Ornate Hawk-Eagle

The Ornate Hawk-Eagle is a species of bird of prey found in Central and South America.

It is known for its striking appearance, with a distinctive crest of feathers on its head, a dark brown body, and white underparts with black barring. 

They hunt from perches, diving down to capture their prey with their paws. 

Fun Fact: It can even take prey that’s twice its size!

16. Olm

The olm is a species of aquatic salamander that is also known as the “human fish.” It is found in underground caves and is well adapted to its dark, subterranean habitat.

 It is also a slow-moving creature and has a long lifespan, living up to 100 years or more. 

Fun Fact: Olms are blind!

17. Olive baboon

The olive baboon, also known as the Anubis baboon, is a species of primate found in Africa. They are named for their olive-coloured fur and are one of the largest baboon species, weighing up to 50 pounds.

Olive baboons are known for their intelligence and are widely studied by scientists and researchers.

Fun fact: Olive Baboons get sexually active at around 35 years.

18. Okapi

The okapi is a species of mammal native to the forests of central and eastern Africa. It’s related to the giraffe and has a similar pattern of distinctive markings on its fur. 

Unlike giraffes, they have much shorter necks and can only reach high branches by standing on their hind legs.

Fun fact: They’ve a specialized tongue to extract the most nutrition from the food. 

19. Ocelot

The ocelot is a type of wild cat native to the Americas. They look like painted leopards because of their distinct fur, marked with black spots and streaks on a yellow or reddish-brown background. 

Ocelots are solitary animals and are highly agile, with the ability to climb trees and swim.  

Fun fact: They almost became extinct in the 20th century due to the demand for their velvety fur.

20. Oryx

The Oryx is a species of antelope found in dry regions of Africa and the Arabian Peninsula. They are known for their long, straight horns and distinctive appearance, with a long neck and legs and a narrow body. 

Oryx are well adapted to their arid habitat and can go without water for long periods.

Fun Fact: Oryx were once extinct in the wild but reintroduced thanks to the captive breeding programs.

21. Ori-Pei

An Ori-Pei is a mixed breed dog from a Pekingese and a Shar Pei. These dogs typically have a distinctive wrinkled appearance and a sturdy, muscular build. 

They are known for being loyal and affectionate pets but can be protective of their owners and may be wary of strangers. 

Fun Fact: They have short noses, so they grunt while breathing.

22. Ornate Box Turtle 

The Ornate Box Turtle (Terrapene ornata ornata) is a species of box turtle native to North America. They are known for their high-domed shells with intricate designs. 

Ornate Box Turtles have a flexible hinge on their bottom shell, which allows them to close themselves inside their shell for protection.

Fun Fact: The distinct coloring helps camouflage the turtle in a damp environment. 

23. Oarfish

The Oarfish is a species of deep-water fish found in tropical waters around the world. Oarfish have a long, ribbon-like body, a small head, and a long, slender dorsal fin that runs the length of their body.

Fun Fact: Oarfish is a record holder in the Guinness World Records book for being the longest species(11 meters) of bony fish.

If you reached the end of this article, then we know you’re a real animal lover. Comment down below which fact interested you the most.

Our website lists animals that start with other letters as well. If you are interested in those, feel free to read up on them.

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