Saprobionten ( ancient Greek σαπρός Sapros , lazy ',' rotten ') are heterotrophic organisms, decomposing organic matter living in dead, so for example, the litter layer of forests, sludge , manure or sludge . This also includes the predators and parasites living in this substrate .
The subset of organisms that feed on dead material are called saprophages . The associated way of life is sometimes referred to as saprobionic. Few authors use the term saprobionts differently as a generic term for saprophytes and saprophages.
In the field of saprobionts there are a large number of terms with partly similar and overlapping meanings:
- Saprophil are organisms, plants or animals that live on or in dead organic substances.
- saprotroph are organisms that use dead organic matter as food. The term is especially common for mushrooms.
saprophag (also saprovor ) are organisms that feed on dead organic matter. Some authors differentiate between subgroups:
- Phytosaprophages, or saprophages in the narrower sense, eat dead plant material. Synonymous is detritivor (also: detritophag), derived from the term detritus .
- Zoo aprophages are generally organisms that feed on dead matter of animal origin. The term is used in particular in parasitology to denote species that feed on tissue that is dying or that has just died , for example in the necrotic tissue of ulcerated wounds.
- Coprophages eat animal excrement.
- Necrophages eat animal carcasses.
- Saprophyte , a plant that lives on dead organic material, was previously used as a name for saprotrophic bacteria and fungi that were treated in botany . However, the actual plants never use dead organic material. In addition, the term was also used for flowering plants without leafy green that rely on fungi for their diet, such as the coral root . However, these are actually parasites of these fungi (see the chapter on symbioses below).
- Saprobians (also: saprobias) are aquatic species (living in fresh water) that are usedas bio-indicators for the classification of water qualitywithin the framework of the so-called saprobic system . The saprobians include saprophage species as well as herbivores and predators with a multitude of different preferred habitats and ways of life. So most of them are not saprobiont.
Saprophages ensure a closed material cycle in an ecosystem . They break down the accumulating organic material and use the accumulating organic molecules for their own energy and building metabolism. Since they are themselves part of the food web of an ecosystem, these organic substances are added to the biogenic cycle .
Functionally, saprophages can be divided into two groups:
- Mineralizers : putrefactive (saprogenic), oxygen-requiring (aerobic) bacteria and fungi break down the organic nutrients into inorganic substances such as carbon dioxide or nitrates , which are needed by the plants as primary producers for the conversion into organic substances (assimilation). Functionally, they are also referred to as destructors .
- Chopper : By chopping up the dead organic material and excreting fine nutrient-rich material (excrement), these animals ensure an enlarged surface area for attack by bacteria and fungi and thus accelerated breakdown and material cycle. These include scavengers (necrophages) such as carrion beetles , crustaceans or vultures , deadwood eaters such as termites or the clock of the dead , substrate eaters such as the lugworm and earthworm and excrement eaters (coprophages) such as the pill turner .
Saprophages are part of communities of organisms ( biocenoses ) that ensure humus formation on land (terrestrial ecosystems) and are responsible for the formation of digested sludge layers ( sapropele ) in bodies of water (aquatic ecosystems) .
Of the organisms living in the soil ( Edaphon ), the saprophagous animal species usually make up a very considerable proportion. In addition to the nutrition of fallen leaves, dead wood, litter and humus, which go back to dead parts of plants, a crucial part of their nutritional basis is the biomass of the mineralizing bacteria and fungi that live in them. So to a large extent they are actually fungus eater (mycetophagus) and bacteria eater (sometimes referred to as microphytophagus), but do not take them up specifically, but rather as part of the decomposed plant biomass, so that these groups are usually treated together. In Central European forest soils, the most important saprophagous soil dwellers are the shell amoeba (Thecamoeba or Testacea), the roundworms (Nematoda), the enchytrae (Enchytraeidae), the earthworms (Lumbricidae), many mites (Acari), especially horn mites , the springtails (Collembola) and the Larvae of two-winged (Diptera) and beetles (Coleoptera).
Saprobionte microorganisms live as symbionts in the digestive tract of mammals (cattle, humans) and insects (termites). There they break down organic substances that cannot be broken down by the host animal's digestive enzymes .
Vascular plants that have little or no chlorophyll have no haustorium - parasites are referred to previously as "saprophytes". However, it has never been proven that vascular plants can feed themselves directly on dead organic matter ( detritus ) , for example through enzymatic digestion . At most, a parasitic symbiosis with saprotrophic fungi is conceivable . But even this possibility is only actually proven in very few cases. Instead, most of the myco-heterotrophic plants live in a parasitic symbiosis with ectomycorrhizal fungi and obtain organic carbon compounds indirectly from their symbiotic partners, the forest trees. This diet is fundamentally different from saprotrophy, it is called epiparasitism . Examples are the two species of spruce asparagus as well as the orchids coral root , bird root root and violet dingel .
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