Microfauna ( and ) are microscopic animals and organisms that exhibit animal-like qualities and have body sizes that are usually <0.1 mm. Microfauna are represented in the animal kingdom (e.g.

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

s, small

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s) and some other heterotrophic, microscopic eukaryotes . A large amount of microfauna are soil microfauna which includes

eukaryotic The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

microbes, rotifers, and nematodes. These types of animal-like eukaryotic microbes and true animals are

heterotroph 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 ...

ic, largely feeding on bacteria. However, some microfauna can consume other things, making them detritivores, fungivores, or even predators.

Habitat

Microfauna are present in every habitat on Earth. They fill essential roles as decomposers and food sources for lower trophic levels, and are necessary to drive processes within larger organisms. Populations of microfauna can reach up to ~10⁷ (~10 million) individuals per g⁻¹ (0.1 g, or 1/10th of a gram) and are very common in plant litter, surface soils, and water films. Many microfauna, such as nematodes, inhabit soil habitats. Plant parasitic nematodes inhabit the roots of various plants, while free-living nematodes live in soil water films. Microfauna also inhabit freshwater ecosystems. For example, freshwater microfauna in Australia include

rotifers The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John Harris ...

, ostracods, copepods, and

cladocerans The Diplostraca or Cladocera, commonly known as water fleas, is a superorder (biology), superorder of small, mostly freshwater crustaceans, most of which feed on microscopic chunks of organic matter, though some forms are predatory. Over 1000 sp ...

. Rotifers are filter feeders that are usually found in fresh water and water films. They consume a variety of things including bacteria, algae, plant cells and organic material. Tardigrades inhabit a variety of

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

s and

moss Mosses are small, non-vascular plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...

es. They need water in these areas to allow for gas exchange and to prevent them from desiccating. Because of this they are considered aquatic. However, they have also been found in all types of environments, ranging from the deep sea to dunes.

Role

One particular example of the role of microfauna can be seen in soil, where they are important in the cycling of nutrients in

ecosystems An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

. The ecological functions of the rhizosphere can be influenced by microfauna, specifically by nematodes and protozoa, which are abundant in soil. For instance, the carbon cycling within the soil can be affected by nematodes who will feed on the roots of plants, impacting the organic carbon in the soil. Similarly, soil protozoa are able to release

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

and

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

into the soil and higher trophic levels by dissolving the organic material and nutrients available. Soil micro-fauna can also impact

microorganism A microorganism, or microbe, is an organism of microscopic scale, microscopic size, which may exist in its unicellular organism, single-celled form or as a Colony (biology)#Microbial colonies, colony of cells. The possible existence of unseen ...

s within the rhizosphere by affecting their diversity and accelerating microorganism turnover. This happens because of the microfauna's selective grazing and their ability to influence the resources within the soil. For example, protozoa can help maintain the quality of the soil by grazing on soil bacteria. Through their grazing, the protozoa can help maintain populations of bacteria, allowing the bacteria to more efficiently decompose dead organic material which will improve the fertility of the soil. Soil microfauna are capable of digesting just about any organic substance and some inorganic substances. These organisms are often essential links in the food chain between primary producers and larger species. For example, zooplankton are widespread microscopic animals and protists that feed on algae and detritus in the ocean, such as foraminifera. Microfauna also aid in digestion and other processes in larger organisms.

Phyla

Examples of notable phyla that include some microfauna: * Microscopic

a: ** Dermatophagoides ("Dust mites") ** Tetranychidae ("Spider mites") ** Some Crustacea ("Crustaceans") *** Copepoda ("Copepods") *** Cladocera ("Water fleas") ***

Ostracod Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...

a ("Seed shrimp") * Tardigrada ("Water bears" or "moss piglets") *

Rotifer The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic Coelom#Pseudocoelomates, pseudocoelomate animals. They were first describ ...

a ("Wheel animals") * Nematoda ("Roundworms") * Loricifera, these are recently discovered anaerobic species, which spend their entire lives in an anoxic environment. File:Yellow_mite_(Tydeidae)_Lorryia_formosa_2_edit.jpg,

Arachnid Arachnids are arthropods in the Class (biology), class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, opiliones, harvestmen, Solifugae, camel spiders, Amblypygi, wh ...

('' Lorryia formosa'') File:Habrotrocha_rosa_1.jpg, Rotifera ('' Habrotrocha rosa''), type of rotifer only found in the leaves of '' Sarracenia purpurea'' File:Tardigrade_(50594150046).jpg, Tardigrade that was extracted from

File:CelegansGoldsteinLabUNC.jpg, Nematoda ('' Caenorhabditis elegans'')

Similar concepts

Macrofauna vs Microfauna

Macrofauna are organisms that are greater than 2 mm in size that usually inhabit soft sediments. They are also found in the benthic zone, and are suspension feeders or deposit feeders. They are important to the marine food web as they are preyed upon by other organisms. Macrofauna, such as flatworms, are able to be separated into small parts through fragmentation, and are able to decompose organic matter. Size_classification_of_soil_organisms

Microflora vs Microfauna

Microflora are organisms that reside within intestines and assist with the digestion of food. In soil, there are three main groups of microflora: viruses, fungi and bacteria.

References

External links

The role of soil microfauna in Plant disease suppression. University of California
{{Authority control Zoology Microscopic animals