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".
Evolutionary history 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).
Classification
By mode of ingestion Modes of feeding include:
Filter feeding: a form of food procurement in which food particles or small organisms are randomly strained from water Deposit feeding: obtaining nutrients from particles suspended in soil Fluid feeding: obtaining nutrients by consuming other organisms' fluids Predation: obtaining nutrients by eating all of an organism Ram feeding and suction feeding: ingesting prey via the fluids around it
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
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. Another classification refers to the specific food animals specialize in eating, such as:
Carnivore: the eating of animals Araneophagy: eating spiders Avivore: eating birds Corallivore: eating coral Durophagy: eating hard-shelled or exoskeleton bearing organisms Egg predator: eating eggs (but also see "Intrauterine cannibalism" below), also Ovivore Haematophage/Sanguivore: eating blood Insectivore: eating insects Myrmecophage: eating ants and/or termites Invertivore: eating invertebrates Keratophagy or Ceratophagy: eating keratin-based material, such as wool by cloths moths, or snakes eating their own skin after ecdysis. Lepidophagy: eating fish scales Molluscivore: eating molluscs Mucophagy: eating mucus Ophiophagy: eating snakes Piscivore: eating fish Anurophagy: eating frogs Spongivore: eating sponges Teuthophagore: eating mainly squid and other cephalopods Vermivore: eating worms Zooplanktonivore: eating zooplankton Herbivore: the eating of plants Exudativore: eating plant and/or insect exudates (gum, sap, lerp, etc.) Gummivore: eating tree sap or gum Folivore: eating leaves Florivore: eating flower tissue prior to seed coat formation Frugivore: eating fruits Graminivore: eating grasses Granivore: eating seeds Nectarivore: eating nectar Palynivore: eating pollen Xylophage: eating wood Algivore: eating algae (both macroalgae and microalgae) Phytoplanktonivore: eating phytoplankton Omnivore: the eating of both plants, animals, fungi, bacteria etc. The term means "all-eater". By amount of meat in diet Hypercarnivore: more than 70% meat Mesocarnivore: 30–70% meat Hypocarnivore: less than 30% meat Fungivore: the eating of fungus Bacterivore: the eating of bacteria The eating of non-living or decaying matter:
Coprophage: eating faeces Detritivore: eating particulate decaying organic matter Geophagia: eating inorganic earth Necrophage: eating carrion Osteophage: eating bones Saprophage: eating or metabolising decaying organic matter Scavenger: eating carrion, refuse or other decaying organic matter There are also several unusual feeding behaviours, either normal, opportunistic, or pathological, such as:
Cannibalism: feeding on members of the same species Anthropophagy: the practice of eating human flesh Autocannibalism: feeding on parts of one's own body (see also autophagy) Filial cannibalism Intrauterine cannibalism Oophagy or ovophagy: the embryo/foetus eats sibling eggs Embryophagy: the foetus eats sibling embryos Sexual cannibalism: cannibalism after mating Kleptoparasitism: stealing food from another animal Kleptopharmacophagy: act of stealing chemical compounds for consumption Lignophagia: eating wood, typically a pathological condition in some domestic animals Paedophagy: eating young animals 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. Placentophagy: eating placenta Trophallaxis: eating food regurgitated by another animal Zoopharmacognosy: self-medication by eating plants, soils, and insects to treat and prevent disease An opportunistic feeder sustains itself from a number of different food sources, because the species is behaviourally sufficiently flexible.
Storage behaviours Some animals exhibit hoarding and caching behaviours in which they store or hide food for later use.
See also Consumer-resource systems Dinosaur diet and feeding List of abnormal behaviours in animals Ingestive behaviors — The physiological behaviors of feeding
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