Heterotrophs are what kind of organisms?
Nutrition is a kind of process in which the body receives the necessary energy and nutrients for cellular metabolism, repair and growth.
Heterotrophs: a general characteristic
Heterotrophs are those organisms thatuse organic power sources. They can not create organic substances from inorganic substances, as autotrophs (green plants and some prokaryotes) do in the process of photo- or chemosynthesis. That is why the survival of the described organisms depends on the activity of autotrophs.
It should be noted that heterotrophs are a person,animals, fungi, and also a part of plants and microorganisms that are incapable of photo- or chemosynthesis. I must say that there is a certain kind of bacteria that use the energy of light to form their own organic substances. These are photoheterotrophs.
Heterotrophs receive food in various ways. But they all boil down to the main three processes (digestion, absorption and assimilation), in which complex molecular complexes split up into simpler ones and are absorbed by tissues and then used for the needs of the organism.
Classification of heterotrophs
All of them are divided into 2 large groups - consumersand decomposers. The latter are the final link in the food chain, since they are able to convert organic compounds into minerals. Consumers are those organisms that use ready-made organic compounds that were formed during the life of autotrophs without their final conversion to mineral residues.
In addition, heterotrophs are saprophytes orparasites. Saprophytes feed on organic compounds of dead organisms. This is the majority of animals, yeast, mold and hats, as well as bacteria that cause the processes of fermentation and decay.
Parasites feed on organic compoundsliving organisms. They include some protozoa, parasitic worms, blood-sucking insects and mites. This group also includes viruses and pathogenic bacteria, parasitic plants-heterotrophs (eg, mistletoe) and fungi-parasites.
Nutrition of heterotrophic organisms
By the nature of nutrition heterotrophs can be veryvarious. So, among them there are herbivorous or carnivorous species, parasites and predators, organisms that eat dead plant fibers or animal carcasses as food, as well as forms that use dissolved organic substances for their nutrition.
If we talk about the types of heterotrophic nutrition, we should mention the holozoic form. Such food, as a rule, is typical for animals and includes the following stages:
- Capture food and swallow it.
- Digestion. It involves splitting organic molecules into smaller particles that dissolve more readily in water. It should be noted that first mechanical grinding of food (for example, teeth) takes place, followed by special digestive enzymes (chemical digestion).
- Suction. Nutrients either immediately enter the tissues, or first into the blood, and then with its current into various organs.
- Assimilation (assimilation process). It consists in the use of nutrients.
- Excretion is the excretion of final products of metabolism and undigested food.
As already noted, organisms thatfeed on dead organic remains, called saprophytes. For the digestion of food, they secrete the corresponding enzymes, and then absorb the substances formed as a result of such extracellular digestion. Mushrooms are heterotrophs, which are inherent in the saprophytic type of food - for example, yeast or fungi Mucor, Rhizppus. They live on a nutrient medium and secrete enzymes, and the thin and branched mycelium provides a significant suction surface. In this case, glucose goes to the process of breathing and providing fungi with energy, which is used for metabolic reactions. I must say that many bacteria are also saprophytes.
It should be noted that many compounds thatare formed when feeding saprophytes, they are not absorbed by them. These substances enter the environment, after which they can be used by plants. That is why the activity of saprophytes plays an important role in the circulation of substances.
The concept of symbiosis
The term "symbiosis" was introduced by the scientist de Bari, who noted that there are associations or close relationships between organisms of different species.
So, there are such bacteria-heterotrophs,which live in the digestive tract of herbivorous mice. They are able to digest cellulose by eating it. These microorganisms can survive in the anaerobic conditions of the digestive system and break down cellulose to simpler compounds that the host animals are able to digest and assimilate. Another example of such symbiosis can be named plants and root nodules of bacteria of the genus Rhizobium.
If we talk about the coexistence of variousorganisms, we should mention such a phenomenon as parasitism. With him, one of them (the parasite) benefits from such coexistence, while the other is only harm (the master). Thus, in this case the parasite extracts not only nutrients from the person on whom it lives, but also takes refuge in it.
Parasites living on external surfaceshost, are called ectoparasites (fleas, mites or leeches). They lead not only a parasitic way of life. The internal ones are obligate. They are characterized only by parasitic existence (for example, pork tapeworm, plasmodia or hepatic fluke).
Summarizing, it can be argued that heterotrophs are an extremely broad group of living beings that not only interact with each other, but also are able to influence other organisms.