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Nutrition or nutrition ( late Latin nutritio 'nutrition' , Latin nutrire 'nourish' ) is the absorption of organic and inorganic substances that are present in food in solid, liquid, gaseous or dissolved form. With the help of these substances the body substance is built up or renewed and the energy requirements necessary for all life processes are covered.

In the ecology is studied, which claims a living being with regard to the diet to its environment presents ( autecology ) in which interactions it is in the diet to other beings ( Synecology ) and its impact on the development of a population have these relationships ( population ecology ). In addition, the total nutrient supply ( trophy ) of an ecosystem is examined in ecology .

Different branches of biology deal with other aspects of nutrition:

Food types

A classification of living beings according to food types is based on the food source, i.e. what they feed on. In animals, there is a connection between their food spectrum and the formation of the mouthparts and the digestive tract. As a rule, an animal does not only feed on one type of food. Many carnivores, for example, eat plants regularly, albeit in small quantities. On the other hand, herbivores do not consume animals as food.

The Greek suffix -phage or -phagie comes from ancient Greek φαγεῖν phageín , German for ' to eat' . The suffix -vore comes from the Latin vorare ' to devour' .

German Greek foreign word Name of the behavior Latin foreign word Greek Latin
scavenger Necrophage Necrophagy νεκρός nekrós 'dead'
Omnivores Pantophage Pantophagy omnivore παντος pantos 'everything' omnis 'everything'
Ant-eater Myrmecophage Myrmecophagy μύρμηκος mýrmekos ' ant '
"Detritus eater" Detritovore detritus 'ground up'
"Putrefactive waste" Saprophage Saprophagy Saprovor , Saprobier , Saprobiont , outdated "Saprophyt" σαπρός saprós ' putrid '
Fish eater Piscivorie Piscivore piscis 'fish'
Carnivores Zoophages Zoophagy Carnivores ζῷον zóon 'animal' caro, carnis 'meat'
Fruit eater Fructivory, frugivory Fructivore, frugivore fructus 'fruit'
Wood eater Xylophage Xylophagia ξύλον xylon 'wood'
"Insect eater" *) Entomophage Entomophagy Insectivore insectum 'incised'
Grain eater Granivore granum 'grain'
Feces eater Coprophage Coprophagia κόπρος kopros 'feces'
Herbivores Phytophagous Phytophagy Herbivores φυτόν phytón 'plant' herba 'grass, plant'
Mushroom eater Mycophage, mycetophage Mycophagia, mycetophagia Mykovore μύκης mykés , μύκητος mýketos 'mushroom'
Plankton eater
"Cupcracker" Durophagia durus 'hard'
"Deadwood Eater" Saproxylophage Saproxylophagia
*)The term "insect eater" in the literal sense is problematic because insect eater is also the name of an order of mammals.


The division is made into three main groups:

Specialization types

Depending on the degree of specialization (ecological valence ) in the food spectrum, animals are divided into different groups and subgroups:

  • Food generalists are animals that have a wide range of plant and animal foods. These animals are considered euryphag (Greek. Εὐρύς Eurys , German , wide ' ) or omnivorous (lat. Omnis , everything' ), respectively.
    • Pantophag (Greek παντὸς pantós , German 'everything' ), eating everything edible, are for example pigs , ducks or carp .
    • Polyphagous (Greek πολύς polýs , German 'much' ) are, for example, insectivores , arthropods and big cats . While they mainly feed on one type of food, they accept many different types of that type.
  • Food specialists are animals that have specialized in a few animal or plant species as a source of food. They are collectively referred to as a stenophag (Greek στενός stenós , German 'eng' ).
    • Oligophag (Greek ὀλίγος oligos , German 'little' ) are, for example, some caterpillars or the koala , which can only feed on a few eucalyptus species.
    • Monophag (Greek μόνος monos , German 'alone' ) are living beings that depend on a single animal or plant species as a source of food, for example some parasites .

Type of food intake

According to the food intake method, organisms can be assigned to different types.

Type of food acquisition

According to the technique of obtaining food, animals can be classified into different types:


Plants usually meet their nutritional requirements through photosynthesis ; they are "self-nourishing" ( autotrophic ). Nutrient elements can be absorbed via gaseous, inorganic molecules that contain carbon , hydrogen and oxygen to build up organic molecules. Nutrient salts ( nitrate , phosphate and sulfate ) as well as trace elements such as boron , chlorine , copper , iron , manganese and the like take up land plants with the water from the soil, aquatic plants from the surrounding water.

Among the freely moving, autotrophic protists (single cells) there are also forms that can change to a heterotrophic way of life if necessary (lack of light) ; they are mixotrophic or amphitroph such as Euglena viridis .

Among the plants there are also ways of life that are reminiscent of the food acquisition of animals:

  • Full parasites are plants that cannot photosynthesize and therefore derive part of the assimilate flow of their host plants via suction processes ( haustoria ) . These plants are not green because of the lack of chlorophyll. One example is Rafflesia .
  • Semi-parasites like mistletoe do photosynthesis themselves, but they take water and nutrient salts from the host plant.
  • Mycotrophic plants enter into nutritional symbioses with fungi: The heterotrophic fungi receive assimilates from the plant, which in return receive an improved supply of water and nutrient salt (myco-autotrophic plants, examples: mycorrhiza , lichens ). The myco-heterotrophic or fully mycotrophic plants represent an extreme case of this type of diet: due to a lack of or too low a chlorophyll content, they are no longer able to carry out sufficient photosynthesis and are completely nourished by their mycorrhizal partners, such as Geosiris aphylla .

In order to be able to thrive in soils that do not contain enough nitrogenous nutrient salts, two strategies have developed for plants.

  • Insectivorous plants (colloquially " carnivorous plants ") such as sundew , pitcher plant and sarracenia , water hose and butterwort have developed various trap mechanisms with which they can catch and digest insects .
  • Plants live with heterotrophic organisms that can provide them with the necessary nutrients:
    • Legumes live in symbiosis with nodule bacteria , which convert atmospheric nitrogen into nitrate and pass it on to the host plant. Since the bacteria live in small tissue growths (nodules) at the root of the host plant, this community represents an endosymbiosis .
    • Unicellular green algae are endosymbionts in many coral species, which therefore can only thrive in light.

Stock keeping

All organisms store nutrients in cell organelles , storage tissues or storage organs. In addition, forms of food storage have developed in the animal kingdom:

  • Foragers like the squirrel store supplies for the nutrient-poor winter.
  • Harvest ants (of the genus Messor in the Mediterranean or the genus Pogonomyrmex in North America ) store grass and grain seeds in their burrows.
  • Honey bees store pollen and honey , which they have made from the collected flower nectar for preservation in the honey stomach, in the honeycombs of their burrows.
  • In some desert ants, some individuals, called " honey pots, " store nectar in their stomachs. They wait in special chambers until they are visited by the workers, to whom they then pass on part of the stomach contents.
  • Leaf cutter ants create mushroom gardens in their burrow . The mushrooms have harvested and pre-chewed leaf pieces as a substrate. The mycelium of the mushrooms they cultivate is their only food.

Stock keeping is often associated with an extremely economical use of feed, in which even the smallest residues are used. At the other extreme are animals who use their feed very uneconomically and only ingest small amounts of a portion and leave the rest behind. They are called food wasters . Many fruit eaters are among them.

Brood care

Young animals that are initially unable to feed themselves are either fed on a yolk sac (fish) or fed by their parents. In some birds ( pigeons ), a preliminary digestion takes place in the crop of the parent animals. The food pulp (crop milk ) is passed on to the young animals ( trophallaxis ). In all teat animals , the newborns are nourished by the milk from the mammary glands .

Interactions in the biocenosis

Within a community ( biocenosis ) of an ecosystem, many organisms are dependent on one another due to an exchange of nutrients .

Material cycle

Autotrophic organisms such as green plants produce all organic building and energy materials from the inorganic substances carbon dioxide , water , nitrate , phosphate and sulfate by assimilation . They are therefore called producers . In the dissimilation process , some of these substances are broken down again into inorganic substances for energy generation. P = producer
Organisms, usually bacteria , which convert the resulting organic material (corpses, waste and excretions) back to the inorganic nutrient salts required by the autotrophs, are referred to as reducing agents or destructors . As heterotrophic organisms in an ecosystem, together with the autotrophic organisms, it enables a closed, biological cycle that is linked to the geological cycle of matter (see carbon cycle , nitrogen cycle and sulfur cycle ): D = destructors
Since bacteria are one of the microorganisms , it would take a very long time for them to completely remineralize a large plant body such as a tree. Animals and mushrooms chop and distribute the organic material so that it is possible for the destructors to break it down in a shorter time. Animals and fungi thus accelerate the cycle of materials in an ecosystem. As heterotrophic organisms, they are dependent on the nutrients produced in excess by the producers, so they are called consumers . K = consumers

A hierarchy of nutritional dependencies can be identified within the consumers of an ecosystem (see food chain , food web and food pyramid ): First-order consumers ( primary consumers ) are animals that feed directly from the producers (e.g. herbivores), second-order consumers in turn feed off the first-order consumer and so on, at the end of this hierarchy is the “end consumer” ( top predators ).

Producers are referred to as primary producers because they are the first in the food chain to build up body substance from which consumers feed. Since consumers also build up body substance that other consumers can feed on, these are also referred to as secondary producers.

Destructors in the material cycle

Relationships and interrelationships

There are numerous one-way or reciprocal relationships between individuals in a biocenosis , of which food relationships are currently best studied. These relationships are effective not only at the level of the individual, but also at the level of the populations of the individual species of an ecosystem: The supply of nutrients not only influences the survival and reproductive ability of the individual ( fitness ), but also the development of population density of a species in an ecosystem:


  • Pro-, para- and metabiosis: A → (+) B: living beings or type A supplies living beings or type B with food, which increases B's performance.
  • Antibiosis: A → (-) B: A feeds on B, whereby B is damaged.
  • Abiose: A → (0) B: The presence of A in the same habitat (biotope) has no influence on B (this is usually difficult to prove in natural ecosystems due to numerous unknown parameters and relationships).

Interrelationships In most cases, there are numerous interrelationships between the individuals in an ecosystem. Food relationships can also be combined with other interactions: For example, the honey bee receives pollen and nectar from the flowering plant as food and enables the flower to be pollinated .

Overview of the interrelationships
  intraspecific ( intraspecific ) inter-species ( interspecific )
A (+)(+) B alliance Alliance, symbiosis, mutualism
A (-)(-) B competitor
A (-)(+) B Brood care , parental care , parental care , altruism Predation , parasitism
A (0)(+) B Pro-, para- and metabiosis
A (0)(-) B Antibiosis
A (0)(0) B Abiose

German nutritionist

further reading

Web links

Commons : Diet  - Collection of pictures, videos and audio files
Wikibooks: Nutrition  - Learning and Teaching Materials
Wiktionary: Nutrition  - explanations of meanings, word origins, synonyms, translations


  1. Not to be confused with the taxonomic order of predators ( Carnivora )
  2. Campbell summarizes herbivores (in the real sense) as well as fungus, protist and bacterial eaters under this type of food . Neil A. Cambell: Biology. Spektrum Akademischer Verlag, Heidelberg 1997, ISBN 3-8274-0032-5 .