Feeding is the process by which organisms, typically animals, obtain food. Terminology often uses either the suffix -vore from Latin vorare, meaning 'to devour', or phagy, from Greek φαγειν, meaning 'to eat'.

Polyphagy is the ability of an animal to eat a variety of food, whereas monophagy is the intolerance of every food except of one specific type (see generalist and specialist species).

Classification

By mode of ingestion

There are many modes of feeding that animals exhibit, including:

• filter feeding - obtaining nutrients from particles suspended in water
• deposit feeding - obtaining nutrients from particles suspended in soil
• fluid feeding - obtaining nutrients by consuming other organisms' fluids
• bulk feeding - obtaining nutrients by eating part or all of an organism

By mode of digestion

• Extra-cellular digestion - excreting digesting enzymes and then reabsorbing the products
• Myzocytosis - one cell pierces another using a feeding tube, and sucks out cytoplasm
• Phagocytosis - engulfing food matter into living cells, where it is digested

By food type

Another classification refers to the specific food animals specialize in eating, such as:

• Carnivore - the eating of animals
• Hematophagy - eating blood
• Insectivore - eating insects
• Lepidophagy - eating fish scales
• Man-eater - eating humans
• Molluscivore - eating molluscs
• Mucophagy - eating mucus
• Ophiophagy - eating snakes
• Piscivore - eating fish
• Spongivore - eating sponges
• Herbivore - the eating of plants
• Folivore - eating leaves
• Frugivore - eating fruits
• Graminivore - eating grasses
• Granivore - eating seeds
• Nectarivore - eating nectar
• Palynivore - eating pollen
• Xylophagy - eating wood
• Omnivore - the eating of both plants and animals
• Fungivore - the eating of fungus
• Bacterivore - the eating of bacteria

The eating of non-living or decaying matter:

• Coprophagy - eating faeces
• Detritivore - eating decomposing material
• Geophagy - eating inorganic earth
• Scavenger - eating carrion

There are also several unusual food sources which can give rise to opportunistic or desperate feeding behaviours, such as:

• Cannibalism - feeding on members of the same species
• Self-cannibalism - feeding on parts of one's own body (see also autophagy)
• Sexual cannibalism - cannibalism after mating
• Kleptoparasitism - stealing food from another animal
• Trophallaxis - eating food regurgitated by another animal
• Oophagy - eating eggs
• Ovophagy - eating embryos
• Paedophagy - eating young animals
• Placentophagy - eating placenta

Evolutionary adaptations

In many instances, the specialization of organisms in a specific type of food source has been one of the major causes of evolution of form and function, such as:

• mouth parts and teeth, such as in whales, vampire bats, leeches, mosquitos, predatory animals such as felines and fishes, etc
• distinct forms of beaks in birds, such as in hawks, woodpeckers, pelicans, hummingbirds, parrots, kingfishers, etc.
• specialized claws and other appendages, for apprehending or killing (including fingers in primates)
• changes in body colour for facilitating camouflage, disguise, setting up traps for preys, etc.
• changes in the digestive system, such as the system of stomachs of herbivores, commensalism and symbiosis