20 Animals That Start With O (2023)

collage of animals

Welcome to animals that start with o. Tons of animals have names that start with the letter O. Many of them can be found around you, while some others are a bit more exotic.

Here’s the complete list of animals that start with O:

  • Oak Toad
  • Oarfish
  • Oceanic Whitetip Shark
  • Ocellated Turkey
  • Ocelot
  • Octopus
  • Oenpelli python
  • Okapi
  • Old English Sheepdog
  • Old House Borer
  • Oleander Hawk Moth
  • Olive Baboon
  • Olive python
  • Olive Sea Snake
  • Olm
  • Onagadori Chicken
  • Opah
  • Opossum
  • Oranda Goldfish
  • Orangutan

1. Oak Toad

  • Scientific name: Anaxyrus quercicus
  • Class: Amphibia
  • Order: Anura
  • Family: Bufonidae
  • Habitat: Oak forests and woodlands in the southeastern United States
  • Size: Adults typically grow to 1.5 – 2 inches in length
  • Color: Olive green or brown with black spots and a white belly
  • Call: A loud, repetitive “Bre-Bre-Bre” call, often heard at night during breeding season
  • Life Span: 4-6 years
  • Diet: Small insects, spiders, and other small invertebrates
  • Threats: Habitat loss and degradation, disease (chytridiomycosis)
  • Conservation status: Near threatened
  • Breeding Season: March to May
  • Number of Eggs: Can lay up to 2,000 eggs in a single breeding event.

2. Oarfish

  • Scientific name: Regalecus glesne
  • Class: Actinopterygii
  • Order: Lampridiformes
  • Family: Regalecidae
  • Habitat: Deep waters, typically found in temperate and tropical oceans
  • Size: Can grow up to 56 feet in length, making them the longest bony fish species in the world
  • Color: Silvery with a red dorsal fin
  • Life Span: Unknown
  • Diet: Small crustaceans, squid, and other small pelagic organisms
  • Threats: Habitat destruction, overfishing, and entanglement in fishing gear
  • Conservation status: Data Deficient (not enough information to determine status)
  • Reproduction: Oviparous (lay eggs), with females laying up to 10,000 eggs at a time
  • Distribution: Found in all major oceans, but primarily in the Pacific and Indian Oceans.

3. Oceanic Whitetip Shark

  • Scientific name: Carcharhinus longimanus
  • Class: Chondrichthyes
  • Order: Carcharhiniformes
  • Family: Carcharhinidae
  • Habitat: Open ocean, found in tropical and subtropical waters worldwide
  • Size: Adults can grow up to 14 feet in length
  • Color: Dark gray or bronze with white tips on the dorsal, pelvic, and pectoral fins
  • Life Span: Approximately 20 years
  • Diet: Fish, squid, crustaceans, and marine mammals
  • Threats: Overfishing, bycatch in fishing gear, and habitat loss
  • Conservation status: Endangered
  • Reproduction: Oviparous (lay eggs), with females giving birth to litters of 4 to 14 pups every two to three years
  • Distribution: Found in the Atlantic, Indian, and Pacific Oceans, but populations have declined significantly in recent decades.

4. Ocellated Turkey

  • Scientific name: Meleagris ocellata
  • Class: Aves
  • Order: Galliformes
  • Family: Phasianidae
  • Habitat: Tropical forests in the Yucatan Peninsula and parts of Belize and Guatemala
  • Size: Adult males can reach up to 11-12 lbs and females are smaller at around 6-7 lbs
  • Color: Males have iridescent feathers in shades of blue, green, and copper with a bright red head and yellow eyespot feathers on their tails, while females are more subdued with brown feathers and less prominent eyespots.
  • Life Span: Up to 10 years in the wild
  • Diet: Omnivorous, feeding on seeds, fruits, insects, and small vertebrates.
  • Threats: Habitat loss due to deforestation and hunting for meat and feathers
  • Conservation status: Near Threatened
  • Reproduction: Ocellated turkeys are polygynous, with males performing elaborate courtship displays to attract females. Females lay 8-15 eggs in a shallow nest on the ground and care for the chicks on their own.
  • Distribution: Endemic to the Yucatan Peninsula in Mexico, Belize, and Guatemala.

5. Ocelot

  • Scientific name: Leopardus pardalis
  • Class: Mammalia
  • Order: Carnivora
  • Family: Felidae
  • Habitat: Tropical forests and brushland in Central and South America, and occasionally southern Texas and Arizona in the United States.
  • Size: Adults typically weigh 15 to 35 pounds and measure about 3 feet in length, with males being larger than females.
  • Color: Tan to reddish-brown with black spots and stripes, similar in appearance to a small leopard.
  • Life Span: Up to 20 years in captivity, with wild ocelots typically living up to 8 to 11 years.
  • Diet: Carnivorous, feeding on a variety of small animals such as rodents, birds, reptiles, and fish.
  • Threats: Habitat loss, fragmentation, and degradation, hunting for their fur, and illegal wildlife trade.
  • Conservation status: Least Concern, although some subspecies are endangered or threatened.
  • Reproduction: Ocelots are polygamous, with females giving birth to 1 to 3 kittens after a gestation period of about 79 to 82 days.
  • Distribution: Found in Central and South America, from Mexico down to northern Argentina, with a small population in southern Texas and Arizona in the United States.

6. Octopus

  • Scientific name: Octopus spp.
  • Class: Cephalopoda
  • Order: Octopoda
  • Habitat: Found in all the world’s oceans, from shallow reefs to deep-sea trenches
  • Size: Varies by species, with the smallest species reaching only a few centimeters in length, and the largest species, the Giant Pacific Octopus, reaching over 16 feet in length and weighing over 100 pounds.
  • Color: Can change color and texture rapidly to blend in with their surroundings, often using camouflage to hide from predators or ambush prey.
  • Life Span: Varies by species, with most living for less than five years.
  • Diet: Carnivorous, feeding on a variety of small fish, crustaceans, and mollusks.
  • Threats: Predation by larger animals, habitat destruction, and overfishing
  • Conservation status: Varies by species, with some species considered endangered or vulnerable due to overfishing and habitat destruction.
  • Reproduction: Males use a specialized arm called a hectocotylus to transfer sperm to the female, who lays her eggs in a protected location and cares for them until they hatch.
  • Distribution: Found in all the world’s oceans, from shallow reefs to deep-sea trenches.

7. Oenpelli python

  • Scientific name: Morelia oenpelliensis
  • Class: Reptilia
  • Order: Squamata
  • Family: Pythonidae
  • Habitat: Restricted to rocky outcrops and escarpments in the western Arnhem Land region of Northern Territory, Australia
  • Size: One of the largest pythons in the world, adults can grow up to 13 feet in length.
  • Color: Patterned with black, gold, and cream-colored scales
  • Life Span: Up to 20 years in captivity, with wild individuals likely having shorter lifespans.
  • Diet: Carnivorous, feeding on a variety of small mammals, birds, and reptiles.
  • Threats: Habitat loss and fragmentation due to mining, agriculture, and other human activities.
  • Conservation status: Endangered, with fewer than 500 mature individuals estimated to remain in the wild.
  • Reproduction: Oviparous, with females laying clutches of 10 to 20 eggs in protected areas such as rock crevices or termite mounds.
  • Distribution: Restricted to rocky outcrops and escarpments in the western Arnhem Land region of Northern Territory, Australia.

8. Okapi

  • Scientific name: Okapia johnstoni
  • Class: Mammalia
  • Order: Artiodactyla
  • Family: Giraffidae
  • Habitat: Dense, tropical rainforests in central Africa
  • Size: Adults typically stand about 5 feet tall at the shoulder and weigh around 400 to 600 pounds.
  • Color: Dark brown with white stripes on the legs and rear, similar in appearance to a zebra.
  • Life Span: Up to 20 years in the wild and in captivity.
  • Diet: Herbivorous, feeding on leaves, fruits, and other vegetation.
  • Threats: Habitat loss, poaching for their meat and skin, and civil unrest.
  • Conservation status: Endangered, with fewer than 15,000 individuals estimated to remain in the wild.
  • Reproduction: Females give birth to a single calf after a gestation period of about 14 months, and the calf is weaned at around 6 months of age.
  • Distribution: Found only in the dense, tropical rainforests of central Africa, primarily in the Democratic Republic of Congo.

9. Old English Sheepdog

  • Breed name: Old English Sheepdog
  • Breed group: Herding Group
  • Size: Large, with males typically weighing between 60 to 100 pounds and standing about 22 inches at the shoulder, and females weighing between 50 to 85 pounds and standing about 21 inches at the shoulder.
  • Coat: Thick, shaggy double coat that is typically white with gray or blue markings, requiring regular grooming to prevent matting.
  • Life Span: 10 to 12 years on average.
  • Temperament: Friendly, social, and intelligent, with a playful and outgoing personality.
  • Training: Intelligent and eager to please, Old English Sheepdogs respond well to positive reinforcement training, but can be stubborn at times.
  • Exercise: Moderately active, requiring daily exercise and mental stimulation to prevent boredom and destructive behavior.
  • Health issues: Hip dysplasia, deafness, and eye problems are common health issues in the breed.
  • Popularity: Ranked 70th out of 196 breeds in popularity by the American Kennel Club (AKC).
  • History: Developed in England in the 18th century for driving and protecting herds of sheep, as well as for use as a companion dog.
  • Other names: OES, Bobtail (due to the traditional practice of docking the breed’s tail), and Dulux Dog (due to the breed’s use as a mascot for Dulux paint in the UK).

10. Old House Borer

  • Common name: Old House Borer
  • Scientific name: Hylotrupes bajulus
  • Order: Coleoptera
  • Family: Cerambycidae
  • Habitat: Can infest and cause damage to softwood trees, as well as to wooden structures such as homes, barns, and furniture.
  • Size: Adults can grow up to 25 mm (1 inch) in length, with dark brown or black bodies and long antennae.
  • Lifecycle: Can take up to 10 years to complete, with the larvae feeding on the wood and creating long, winding tunnels that weaken the structure.
  • Damage: Can cause significant damage to wooden structures, as well as reducing the value of timber and causing problems for the timber industry.
  • Distribution: Originally from Europe and Asia, but has been introduced to many parts of the world, including North America, South America, and Australia.
  • Control: Prevention measures such as using treated wood, reducing moisture in buildings, and avoiding storing firewood near buildings can help prevent infestations. Infested wood may need to be removed or treated with insecticides to control an infestation.
  • Impact: The Old House Borer is considered a significant pest in the building and timber industries due to the damage it can cause.

11. Oleander Hawk Moth

  • Common name: Oleander Hawk Moth
  • Scientific name: Daphnis nerii
  • Order: Lepidoptera
  • Family: Sphingidae
  • Habitat: Found in a wide range of habitats, including gardens, parks, agricultural areas, and open woodlands. Native to Africa, Asia, and parts of Europe, but has been introduced to other parts of the world, including North America.
  • Size: Large, with a wingspan of up to 12 cm (4.7 inches).
  • Color: Wings are pink or brown with black and white markings, and the body is a light green color.
  • Lifecycle: Females lay eggs on the leaves of host plants, which are then eaten by the caterpillars. The caterpillars are green with white and black markings and can grow up to 8 cm (3 inches) in length. The adult moth lives for only a few weeks and does not feed.
  • Diet: The caterpillars feed on the leaves of plants in the Apocynaceae family, including oleander, periwinkle, and milkweed.
  • Behavior: Nocturnal, with adults being active at night and resting during the day.
  • Conservation status: Not considered threatened or endangered.
  • Ecological role: As pollinators, Oleander Hawk Moths play an important role in the ecosystems where they live, and the caterpillars provide food for birds and other animals.
  • Economic impact: While not considered a pest, Oleander Hawk Moths can occasionally cause damage to crops, particularly to oleander plants in areas where they have been introduced.

12. Olive Baboon

  • The Olive Baboon (Papio anubis) is a species of Old World monkey that belongs to the family Cercopithecidae.
  • They are found throughout much of sub-Saharan Africa, from Senegal and Ethiopia to Angola and South Africa.
  • Olive baboons are social animals and live in large troops, which can include up to several hundred individuals.
  • Adult males are typically larger than females, with a body length of 60-100 cm (24-39 in) and a weight of 20-40 kg (44-88 lb), while females are 50-70 cm (20-28 in) in length and weigh 10-15 kg (22-33 lb).
  • They have a distinctive olive-green or greyish coat, with a lighter-colored underbelly.
  • Olive baboons are omnivorous and eat a wide range of foods, including fruits, leaves, insects, and small animals.
  • Females typically give birth to a single offspring after a gestation period of around 6 months.
  • Olive baboons are not considered endangered, but their populations are threatened by habitat loss and hunting for bushmeat and traditional medicine.

13. Olive Python

  • The Olive Python (Liasis olivaceus) is a species of python that is found in northern and western Australia.
  • They are one of the largest snake species in Australia, with adults growing up to 4 meters (13 feet) in length and weighing up to 25 kilograms (55 pounds).
  • Olive pythons are non-venomous and use constriction to kill their prey, which includes a variety of mammals and birds.
  • They are nocturnal and typically hunt at night, using their excellent sense of smell to locate prey.
  • Olive pythons are oviparous, meaning they lay eggs, with females laying clutches of up to 30 eggs in a single season.
  • The species is not considered endangered, but their populations are threatened by habitat loss and fragmentation, as well as illegal collection for the pet trade.
  • Olive pythons are an important cultural symbol for some Indigenous Australian communities, and their hunting and use is regulated by traditional laws and practices.

14. Olive Sea Snake

  • The Olive Sea Snake (Aipysurus laevis) is a species of venomous sea snake that is found in the waters of the Indo-Pacific region, including the coasts of Australia, Indonesia, and Papua New Guinea.
  • They are a relatively small species of sea snake, with adults growing up to 1.2 meters (4 feet) in length.
  • Olive sea snakes are easily recognizable by their smooth, olive-green scales, which help them blend in with their surroundings in shallow water.
  • The species feeds on a variety of fish and invertebrates, and is capable of diving to depths of up to 50 meters (165 feet) to hunt for prey.
  • Olive sea snakes are oviparous, with females laying clutches of up to 5 eggs in a single breeding season.
  • They are considered to be relatively docile and are not aggressive towards humans, but their venom is highly toxic and can cause serious illness or death if not treated promptly.
  • The species is not considered endangered, but like many sea snakes, it is threatened by habitat loss, pollution, and accidental entanglement in fishing gear.

15. Olm

  • The Olm (Proteus anguinus) is a species of amphibian that is found in underground caves and rivers in southeastern Europe, including Slovenia, Croatia, and Bosnia and Herzegovina.
  • They are also known as the “human fish” due to their pinkish skin and limbless, eel-like appearance.
  • Olms are adapted to living in complete darkness, and have evolved to have no eyes, and a highly sensitive sense of smell and hearing.
  • They are also able to go without food for up to 10 years, and can survive extreme environmental conditions such as low oxygen levels and cold temperatures.
  • Olms are the only known vertebrate species that exhibits neoteny, which means they retain their juvenile characteristics throughout their entire lifespan, including gills for breathing underwater.
  • The species is considered to be critically endangered, with a population of less than 10,000 individuals, due to habitat loss, pollution, and human disturbance of their underground habitats.
  • Olms are important both ecologically and culturally, and are the subject of ongoing conservation efforts and scientific research.

16. Onagadori Chicken

  • The Onagadori Chicken is a breed of domestic chicken that originated in Japan, and is known for its long, flowing tail feathers.
  • Onagadori chickens can grow tail feathers up to 3 meters (9.8 feet) in length, making them one of the most ornamental breeds of chicken.
  • The breed is also known for its hardiness and adaptability to a wide range of environments, including hot and humid conditions.
  • Onagadori chickens are raised primarily for their ornamental value, and are not typically used for meat or egg production.
  • The breed has been designated as a “National Natural Monument” in Japan, and is protected by law.
  • Due to their unique characteristics and rarity, Onagadori chickens are highly prized by poultry enthusiasts and collectors, and can command high prices on the market.
  • However, the breed is also at risk of inbreeding and genetic loss, and conservation efforts are underway to preserve the genetic diversity of the breed.

17. Opah

  • The Opah (Lampris guttatus) is a large, deep-sea fish that is found in the waters of the Pacific, Atlantic, and Indian Oceans.
  • They are a distinctive fish, with a round body shape, bright red fins, and silver and blue iridescent scales.
  • Opahs are known for their unique adaptations, including a warm-blooded circulatory system that allows them to maintain a body temperature higher than the surrounding water, and a large, fleshy “operculum” on their gill cover that helps them swim efficiently.
  • They are a pelagic fish, meaning they live in open water, and are found at depths of up to 500 meters (1,640 feet).
  • Opahs are a popular game fish and are also caught commercially for their meat, which is considered a delicacy in some parts of the world.
  • The species is not considered endangered, but their populations are threatened by overfishing and accidental bycatch in longline and gillnet fisheries.
  • Opahs are also an important species for scientific research, and have been the subject of extensive studies on their biology, ecology, and evolution.

18. Opossum

  • The Opossum (Didelphimorphia) is a family of marsupial mammals native to the Americas, including North, Central, and South America.
  • There are over 100 different species of opossums, ranging in size from a few inches to over 3 feet in length.
  • Opossums are nocturnal animals and are primarily active at night, although some species may also be active during the day.
  • They are known for their ability to play dead when threatened, which involves falling limp and emitting a foul-smelling odor to deter predators.
  • Opossums are omnivorous and will eat a wide range of foods, including fruits, insects, small mammals, and carrion.
  • They are an important species in many ecosystems, as they help to control pest populations and disperse seeds.
  • Opossums are also important in medical research, as they are the only North American marsupial and can be used to study embryonic development and immunology.
  • The species is not considered endangered, but many species are threatened by habitat loss, disease, and human interference.
  • Opossums have adapted well to living in urban environments and are often seen in suburban areas and backyard gardens.

19. Oranda Goldfish

  • The Oranda Goldfish (Carassius auratus) is a type of freshwater fish that is commonly kept in aquariums and ponds.
  • They are a popular ornamental fish, known for their distinctive appearance, which includes a round, bulbous head and a long, flowing tail fin.
  • Oranda goldfish are typically metallic red, orange, or black, and can grow up to 8 inches in length.
  • They are omnivores, and will eat a variety of foods, including fish flakes, pellets, and live or frozen foods such as brine shrimp and bloodworms.
  • Oranda goldfish are known for their hardiness and adaptability, and can tolerate a wide range of water conditions, including low oxygen levels and high ammonia levels.
  • The species is not considered endangered, but their natural range is limited to parts of China and Korea.
  • Oranda goldfish have been bred extensively in captivity, and there are many different color and fin variations available.
  • They are also popular in competitive breeding and exhibition, with competitions held around the world to showcase the best specimens.
  • Oranda goldfish are relatively easy to care for and make good pets for both beginners and experienced fishkeepers.

20. Orangutan

  • The Orangutan is a large, arboreal ape that is native to the islands of Borneo and Sumatra in Southeast Asia.
  • There are two species of orangutans: the Bornean orangutan (Pongo pygmaeus) and the Sumatran orangutan (Pongo abelii).
  • Orangutans are known for their distinctive red-orange hair, which is longer and shaggier in males than females, and for their long, powerful arms and grasping hands and feet.
  • They are the largest arboreal animal in the world, with males weighing up to 200 pounds (90 kilograms) and standing up to 5 feet (1.5 meters) tall.
  • Orangutans are primarily vegetarian and feed on a variety of fruits, leaves, and insects, although they have been known to eat small animals on occasion.
  • The species is considered critically endangered, with populations declining rapidly due to habitat loss, hunting, and the pet trade.
  • Orangutans are highly intelligent and have been observed using tools and exhibiting a wide range of behaviors, including problem-solving, communication, and social interaction.
  • They are the subject of extensive conservation efforts, including habitat protection, rehabilitation and release programs, and education and awareness campaigns.
  • Orangutans are also important for scientific research, and have been the subject of studies on their genetics, behavior, and physiology.

Conclusion: Animals That Start With O

Here’s the complete list of animals that start with O:

  • Oak Toad
  • Oarfish
  • Oceanic Whitetip Shark
  • Ocellated Turkey
  • Ocelot
  • Octopus
  • Oenpelli python
  • Okapi
  • Old English Sheepdog
  • Old House Borer
  • Oleander Hawk Moth
  • Olive Baboon
  • Olive python
  • Olive Sea Snake
  • Olm
  • Onagadori Chicken
  • Opah
  • Opossum
  • Oranda Goldfish
  • Orangutan

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