Osmotrophy is a feeding mechanism involving the movement of dissolved

organic compounds In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The s ...

osmosis Osmosis (, ) is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential (region of lower solute concentration) to a region of low water potential (region ...

for nutrition. Organisms that use osmotrophy are called osmotrophs. Some

mixotrophic A mixotroph is an organism that can use a mix of different sources of energy and carbon, instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other. It is estimated that mixotrophs com ...

microorganisms A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

use osmotrophy to derive some of their

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of ...

. Osmotrophy is used by a diversity of organisms. Organisms that use osmotrophy include bacteria, many species of

protists A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...

and most

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

. Some macroscopic animals like molluscs, sponges, corals, brachiopods and

echinoderms An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the ...

may use osmotrophic feeding as a supplemental

food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is in ...

source.

Process

Osmotrophy as a means of gathering

nutrients A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excr ...

microscopic The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded as the scale be ...

organisms relies on cellular surface area to ensure that proper

diffusion Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical ...

of nutrients occur in the

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

. In other words, an osmotroph is an organism that has their "stomach" outside of their body. Sometimes, osmotrophs may still have an internal digestive system in addition to still using osmosis as a way to gain supplemental nutrients. Additionally, when

organisms In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fu ...

increase in size, the surface area per volume ratio drops and osmotrophy becomes insufficient to meet

nutrient A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excre ...

demands. Larger macroscopic organisms that rely on osmotrophy can compensate for a reduced surface area per volume ratio with a very flat, thin body. A tapeworm is an example of such adaptation. In stagnant waters photoautotrophs have a relative advantage over

heterotrophic A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...

osmotrophs since the flux of photons as an

source are not hindered at low temperatures, thus it depends on

for mass acquisition through Brownian diffusion. Osmotrophy differs from other cellular feeding mechanisms, but can also be found in a diversity of organisms. This allows for organisms to use

in different environments.

Fungi

Fungi are the biggest osmotrophic specialist since they are major degraders in all ecosystems. For organisms like fungi, osmotrophy facilitates the decomposition process. This is a result of the Osmotrophy resulting in metabolites that continue growth.

Process

Fungi

References

Further reading

See also