Feeding is the process by which organisms, typically animals, obtain food. Terminology often uses either the suffixes -vore, -vory, or -vorous from Latin vorare, meaning "to devour", or -phage, -phagy, or -phagous from Greek φαγεῖν (phagein), meaning "to eat".
The evolution of feeding is varied with some feeding strategies evolving several times in independent lineages. In terrestrial vertebrates, the earliest forms were large amphibious piscivores 400 million years ago. While amphibians continued to feed on fish and later insects, reptiles began exploring two new food types, other tetrapods (carnivory), and later, plants (herbivory). Carnivory was a natural transition from insectivory for medium and large tetrapods, requiring minimal adaptation (in contrast, a complex set of adaptations was necessary for feeding on highly fibrous plant materials).[1]
"Polyphagy" redirects here. For increased appetite as a medical symptom, see polyphagia.
Polyphagy is the habit in an animal species, of eating and tolerating a relatively wide variety of foods, whereas monophagy is the intolerance of every food except for one specific type (see generalist and specialist species). Oligophagy is a term for intermediate degrees of selectivity, referring to animals that eat a relatively small range of foods, either because of preference or necessity.[2]
Another classification refers to the specific food animals specialize in eating, such as:
Pica: appetite for largely non-nutritive substances, e.g. clay or hair, sometimes in pregnancy or in pathological states, typically a medical or veterinary concern.
