Omnivore

Lore & Background

The word omnivore was coined by the French and later adopted by the English in the 1800s. Traditionally, the definition was entirely behavioral, meaning simply 'including both animal and vegetable tissue in the diet.' In more recent times, with advanced technological capabilities in gastroenterology, biologists formulated a standardized variation used for labeling a species' actual ability to obtain energy and nutrients from materials, conditioning two context-specific definitions: behavioral and physiological. The behavioral definition specifies if a species or individual is actively consuming both plant and animal materials, while the physiological definition specifies species that have the capability to obtain energy and nutrients from both plant and animal matter.

Reader's Guide

The concept of omnivore is significant because it describes a feeding strategy that provides food security in stressful times or makes possible living in less consistent environments. However, the taxonomic utility of the traditional and behavioral definition is limited, since the diet, behavior, and phylogeny of one omnivorous species may be very different from another. No taxonomic equivalent to Carnivora exists for omnivores, as omnivores are widespread across multiple taxonomic clades. The classification 'omnivore' refers to the adaptation and main food source of the species in general, so exceptions such as herbivores eating meat or carnivores eating plant matter do not make either individual animals or the species as a whole omnivorous. Some researchers argue that evolution of any species from herbivory to carnivory or carnivory to herbivory would be rare except via an intermediate stage of omnivory.

Did You Know?

• Dogs evolved from primarily carnivorous organisms (Carnivora) while pigs evolved from primarily herbivorous organisms (Artiodactyla).
• Frugivores include cassowaries, orangutans, humans, and grey parrots; insectivores include swallows and pink fairy armadillos; granivores include large ground finches and mice.
• Polar bears are classified as carnivores both taxonomically (order Carnivora) and behaviorally, despite being in a genus where most species are omnivores.
• American alligators (Alligator mississippiensis) may be physiologically omnivorous, as investigations suggested they probably ate fruits both accidentally and deliberately.