Circular dendrogram of feeding behaviours
A mosquito drinking blood (hematophagy) from a human (note the droplet of plasma being expelled as a waste)
A rosy boa eating a mouse whole
A red kangaroo eating grass
The robberfly is an insectivore, shown here having grabbed a leaf beetle
An American robin eating a worm
Hummingbirds primarily drink nectar
A krill filter feeding
A Myrmicaria brunnea feeding on sugar crystals

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).[1]

Evolutionary adaptations

The specialization of organisms towards specific food sources is one of the major causes of evolution of form and function, such as:

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 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 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).

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

The eating of non-living or decaying matter:

There are also several unusual feeding behaviours, either normal, opportunistic, or pathological, such as:

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

References

  1. ↑ Sahney, S., Benton, M.J. & Falcon-Lang, H.J. (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica" (PDF). Geology. 38 (12): 1079–1082. doi:10.1130/G31182.1.{{cite journal}}: CS1 maint: multiple names: authors list (link)

Notes

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