Editing Gastrotrich (section)

==Distribution and habitat==
[[File:Gatrotricha (South Africa).jpg|thumb|right|A & B = Macrodasyida<br/>C, D, E & F = Chaetonotida]]
Gastrotrichs are [[Cosmopolitan distribution|cosmopolitan]] in distribution. They inhabit the interstitial spaces between particles in marine and freshwater environments, the surfaces of aquatic plants and other submerged objects and the surface film of water surrounding soil particles on land.<ref name=Todaro/> They are also found in stagnant pools and anaerobic mud, where they thrive even in the presence of [[hydrogen sulfide]]. When pools dry up they can survive periods of desiccation as eggs, and some species are capable of forming [[Microbial cyst|cysts]] in harsh conditions.<ref>{{cite book |title=The Ecology of Soil Decomposition: Gastrotrichs |last=Adl |first=Sina M. |year=2003 |publisher=CABI |isbn=978-0-85199-661-5 |page=52 |url=https://books.google.com/books?id=vePuN8aYhyEC&q=gastrotrich+terrestrial+soil&pg=PA52 }}</ref>  In marine sediments they have been known to reach 364 individuals per {{convert|10|cm2|1|abbr=on}} making them the third most common invertebrate in the sediment after [[nematode]]s and [[Harpacticoida|harpacticoid copepods]]. In freshwater they may reach a density of 158 individuals per {{convert|10|cm2|1|abbr=on}} and are the fifth most abundant group of invertebrates in the sediment.<ref name=Todaro/>