View source for Infusoria

{{Short description|Microorganisms in freshwater ponds}}

[[File:Die_Frau_als_Hausärztin_(1911)_043_Wassertropfen_aus_gestandenem_Wasser.png | thumb | right | alt=An illustration of various creature in a water drop  | Illustration of a water drop from stagnant water]]
'''Infusoria''' is a word used to describe various freshwater [[microorganism]]s, including [[ciliate]]s, [[copepods]], [[Euglena|euglenoids]], [[planktonic]] [[crustacean]]s, [[protozoa]], [[unicellular algae]] and small [[invertebrate]]s. Some authors (e.g., [[Otto Bütschli|Bütschli]]) have used the term as a synonym for [[Ciliophora]]. In modern, formal classifications, the term is considered obsolete; the microorganisms previously and colloquially referred to as Infusoria are mostly assigned to the clades [[Diaphoretickes]] (e.g. ciliates, most algae), [[Amorphea]] (e.g. crustaceans and other small animals) and [[Discoba]] (euglenids).

In other contexts, the term is used to define various aquatic microorganisms found in decomposing matter.<ref>{{Cite web |title=Definition of INFUSORIAN |url=https://www.merriam-webster.com/dictionary/infusorian |access-date=2023-02-16 |website=www.merriam-webster.com |language=en |archive-date=2023-02-16 |archive-url=https://web.archive.org/web/20230216222718/https://www.merriam-webster.com/dictionary/infusorian |url-status=live }}</ref>

==Aquarium use==
Certain microorganisms, including [[cyclops (copepod)|cyclops]] and [[daphnia]] (among others), are sold as a supplemental [[fishkeeping|fish food]]. Some fish stores or pet shops may have these infusoria available for live purchase, but typically they are sold in frozen cubes—for example, by the Japan-based fish food brand [[Hikari (company)|Hikari]]. Still, some advanced [[aquarist]]s, with especially large collections of fish, will breed and cultivate their own supplies of the microorganisms.

Infusoria are especially used by aquarists and fish breeders to feed fish [[Spawn (biology)#Fry|fry]]; because of their small sizes, infusoria can be used to rear newly-hatched offspring of many common (and also less common) aquarium species. Many average home aquaria are unable to naturally supply sufficient infusoria for fish-rearing, so hobbyists may create and maintain their own [[Microbiological culture|cultures]], either through utilizing their own existing aquarium water or by using one of the many commercial cultures available.<ref>Sharpe, Shirlie (December 22, 2018). [https://www.thesprucepets.com/what-is-infusoria-1379895 "How to Culture Your Own Infusoria at Home"] {{Webarchive|url=https://web.archive.org/web/20190818200443/https://www.thesprucepets.com/what-is-infusoria-1379895 |date=2019-08-18 }}. The Spruce Pets. Retrieved August 28, 2019.</ref> 

Infusoria can be cultured at-home by soaking any decomposing vegetative matter, such as [[papaya]] or [[cucumber]] peels, in a jar of aged (i.e., chlorine-free) water, preferably from an existing aquarium setup. The culture starts to proliferate in two to three days, depending on temperature and light received. The water first turns cloudy because of a rise in levels of bacteria, but clears up once the infusoria consume them. At this point, the infusoria are usually visible to the naked eye as small, white [[motile]] specks. They can be easily fed to fish with the use of a large turkey-baster or by gently scooping with a very fine net. Additionally, the water in which the infusoria are kept in can be changed periodically, even one to two times per week, by draining and replacing up to 50% of the volume of water (for hygienic and maintenance purposes).

==See also==
* [[Animalcule]]s

== References ==
{{Reflist}}

==Bibliography==
* Ratcliff, Marc J. (2009). The Emergence of the Systematics of Infusoria. In: [https://books.google.com/books?id=GTZt1c5IYioC ''The Quest for the Invisible: Microscopy in the Enlightenment'']. Aldershot: Ashgate.

==External links==
{{wikispecies|Infusoria}}
{{EB1911 Poster|Infusoria}}
* [http://www.microscopyu.com/moviegallery/pondscum/ Types of Protozoans and video]
* [http://www.microscopy-uk.org.uk/index.html?http://www.microscopy-uk.org.uk/pond/index.html Pond Life Identification Kit]

{{Aquarium}}
{{Protist structures}}

[[Category:Fishkeeping]]
[[Category:Obsolete eukaryote taxa]]


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