Microfauna

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, ostracods, copepods, and cladocerans.{{Cite web |last=Walsh |first=Robert |title=Australian Waterline |url=https://wetlandinfo.des.qld.gov.au/resources/static/pdf/ecology/microfauna/australian-waterlife-freshwater-microfauna.pdf}} 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 lichens and mosses. They need water in these areas to allow for gas exchange and to prevent them from desiccating.{{Cite web |date=2020-03-13 |title=Tardigrade |url=https://www.nationalgeographic.com/animals/invertebrates/facts/tardigrades-water-bears |access-date=2024-03-25 |website=Animals |language=en}} 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.

File:Model_of_the_plant_microbiome_(phytobiome).jpg and the rhizosphere.]]

One particular example of the role of microfauna can be seen in soil, where they are important in the cycling of nutrients in ecosystems.{{cite book|last1=Aescht|first1=E|last2=Foissner|first2=W|year=1996|chapter=Microfauna|editor1-last=Schinner|editor1-first=F|editor2-last=Öhlinger|editor2-first=R|editor3-last=Kandeler|editor3-first=E|editor4-last=Margesin|editor4-first=R|title=Methods in Soil Biology|pages=316–337|publisher=Springer|location=Berlin, Heidelberg|doi=10.1007/978-3-642-60966-4_22|isbn=978-3-642-64633-1}} 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 and nitrogen into the soil and higher trophic levels by dissolving the organic material and nutrients available.{{Cite journal |last1=Vaerewijck |last2=Houf |title=4 - The role of free-living protozoa in protecting foodborne pathogens |url=https://www.sciencedirect.com/science/article/abs/pii/B9781782421078500049 |journal=Woodhead Publishing Series in Food Science, Technology and Nutrition |date=January 2015 |volume=2 |pages=81–101 |doi=10.1533/9781782421153.1.81 |isbn=978-1-78242-107-8 |via=Science Direct}}

Soil micro-fauna can also impact microorganisms 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.{{Cite journal |last1=Chen |first1=Xiaoyun |last2=Liu |first2=Manqiang |last3=Hu |first3=Feng |last4=Mao |first4=Xiaofang |last5=Li |first5=Huixin |date=2007-08-01 |title=Contributions of soil micro-fauna (protozoa and nematodes) to rhizosphere ecological functions |url=https://www.sciencedirect.com/science/article/pii/S1872203207600687 |journal=Acta Ecologica Sinica |volume=27 |issue=8 |pages=3132–3143 |doi=10.1016/S1872-2032(07)60068-7 |bibcode=2007AcEcS..27.3132C |issn=1872-2032}} 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.{{Cite web |title=Protozoan - Cell Structure, Nutrition, Reproduction {{!}} Britannica |url=https://www.britannica.com/science/protozoan/Form-and-function |access-date=2024-03-28 |website=britannica.com |language=en}}

Soil microfauna are capable of digesting just about any organic substance and some inorganic substances.{{cn|date=July 2022}} 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.

Examples of notable phyla that include some microfauna:

• Microscopic arthropoda:
• Dermatophagoides ("Dust mites")
• Tetranychidae ("Spider mites")
• Some Crustacea ("Crustaceans")
• Copepoda ("Copepods")
• Cladocera ("Water fleas")
• Ostracoda ("Seed shrimp")
• Tardigrada ("Water bears" or "moss piglets")
• Rotifera ("Wheel animals")
• Nematoda ("Roundworms")
• Loricifera, these are recently discovered anaerobic species, which spend their entire lives in an anoxic environment.{{cite journal |last1=Fang |first1=Janet |date=6 April 2010 |title=Animals thrive without oxygen at sea bottom |journal=Nature |volume=464 |issue=7290 |pages=825 |doi=10.1038/464825b |pmid=20376121 |doi-access=free|bibcode=2010Natur.464..825F }}{{cite news |date=9 April 2010 |title=Briny deep basin may be home to animals thriving without oxygen |url=https://www.sciencenews.org/article/briny-deep-basin-may-be-home-animals-thriving-without-oxygen |work=Science News}}

File:Yellow_mite_(Tydeidae)_Lorryia_formosa_2_edit.jpg|Arachnid (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 moss

File:CelegansGoldsteinLabUNC.jpg|Nematoda (Caenorhabditis elegans)

Macrofauna are organisms that are greater than 2 mm in size that usually inhabit soft sediments.{{Cite journal |last1=Heděnec |first1=Petr |last2=Jiménez |first2=Juan Jose |last3=Moradi |first3=Jabbar |last4=Domene |first4=Xavier |last5=Hackenberger |first5=Davorka |last6=Barot |first6=Sebastien |last7=Frossard |first7=Aline |last8=Oktaba |first8=Lidia |last9=Filser |first9=Juliane |last10=Kindlmann |first10=Pavel |last11=Frouz |first11=Jan |date=2022-10-17 |title=Global distribution of soil fauna functional groups and their estimated litter consumption across biomes |journal=Scientific Reports |volume=12 |issue=1 |pages=17362 |doi=10.1038/s41598-022-21563-z |issn=2045-2322 |pmc=9576680 |pmid=36253487|bibcode=2022NatSR..1217362H }} They are also found in the benthic zone, and are suspension feeders or deposit feeders.{{Citation |last=Watling |first=Les |title=Macrofauna |date=2019-01-01 |encyclopedia=Encyclopedia of Ocean Sciences (Third Edition) |pages=728–734 |editor-last=Cochran |editor-first=J. Kirk |url=https://www.sciencedirect.com/science/article/pii/B9780124095489110693 |access-date=2024-03-01 |place=Oxford |publisher=Academic Press |isbn=978-0-12-813082-7 |editor2-last=Bokuniewicz |editor2-first=Henry J. |editor3-last=Yager |editor3-first=Patricia L.}} 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.{{Citation |last1=Maurya |first1=Anurag |title=Chapter 7 - Biofiltration technique for removal of waterborne pathogens |date=2020-01-01 |work=Waterborne Pathogens |pages=123–141 |editor-last=Vara Prasad |editor-first=Majeti Narasimha |url=https://www.sciencedirect.com/science/article/pii/B9780128187838000074 |access-date=2024-03-01 |publisher=Butterworth-Heinemann |isbn=978-0-12-818783-8 |last2=Singh |first2=Manoj Kumar |last3=Kumar |first3=Sushil |editor2-last=Grobelak |editor2-first=Anna}}

File:Size_classification_of_soil_organisms.jpg

Microflora are organisms that reside within intestines and assist with the digestion of food.{{Cite web |date=2011-02-02 |title=National Cancer Institute |url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/microflora# |access-date=2024-03-01 |website=cancer.gov |language=en}} In soil, there are three main groups of microflora: viruses, fungi and bacteria.

• Fauna
• Megafauna
• Mesofauna

{{Reflist}}

• [https://web.archive.org/web/20080516224017/http://www.sarep.ucdavis.edu/NEWSLTR/v6n4/sa-8.htm The role of soil microfauna in Plant disease suppression. University of California]

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Category:Zoology

Category:Microscopic animals