Examples of omnivores. From left to right: Humans,[1] dogs,[2] pigs, walking catfish, American crow, gravel ant.

An omnivore (/ˈɒmnɪvɔːr/) is an animal that has the ability to eat and survive on both plant and animal matter.[3] Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutrients and energy of the sources absorbed.[4] Often, they have the ability to incorporate food sources such as algae, fungi, and bacteria into their diet.[5][6][7]

Omnivores come from diverse backgrounds that often independently evolved sophisticated consumption capabilities. For instance, dogs evolved from primarily carnivorous organisms (Carnivora) while pigs evolved from primarily herbivorous organisms (Artiodactyla).[8][9][10] Despite this, physical characteristics such as tooth morphology may be reliable indicators of diet in mammals, with such morphological adaptation having been observed in bears.[11][12]

The variety of different animals that are classified as omnivores can be placed into further sub-categories depending on their feeding behaviors. Frugivores include maned wolves and orangutans;[13][14] insectivores include swallows and pink fairy armadillos;[15][16] granivores include large ground finches and mice.

All of these animals are omnivores, yet still fall into special niches in terms of feeding behavior and preferred foods. Being omnivores gives these animals more food security in stressful times or makes possible living in less consistent environments.[17]