scuticociliate

{{Short description|Subclass of single-celled organisms}}

{{Automatic taxobox

| taxon = Scuticociliatia

| authority = Small, 1967{{cite journal|last1=Small|first1=Eugene B.|title=The Scuticociliatida, a New Order of the Class Ciliatea (Phylum Protozoa, Subphylum Ciliophora)|journal=Transactions of the American Microscopical Society|date=October 1967|volume=86|issue=4|pages=345|doi=10.2307/3224258}}

| subdivision_ranks = Orders

| subdivision =

• Philasterida
• Pleuronematida
• Thigmotrichida

}}

Scuticociliatia is a subclass of ciliates in the class Oligohymenophorea. Its members are called scuticociliates. These unicellular eukaryotes are microorganisms that are usually free-living and can be found in freshwater, marine, and soil habitats.{{Cite journal |last=Pan |first=Mengmeng |last2=Chen |first2=Ying |last3=Liang |first3=Chengdong |last4=Pan |first4=Xuming |date=2020-06-01 |title=Taxonomy and molecular phylogeny of three freshwater scuticociliates, with descriptions of one new genus and two new species (Protista, Ciliophora, Oligohymenophorea) |url=https://www.sciencedirect.com/science/article/pii/S0932473919300811 |journal=European Journal of Protistology |volume=74 |pages=125644 |doi=10.1016/j.ejop.2019.125644 |issn=0932-4739}} Around 20 members of the group have been identified as causative agents of the disease scuticociliatosis, in which the ciliates are parasites of other marine organisms. Species known to be susceptible include a broad range of teleosts, seahorses, sharks, and some crustaceans.{{cite book|last1=Jung|first1=Sung-Ju|last2=Woo|first2=Patrick T.K.|editor1-last=Woo|editor1-first=Patrick T.K.|editor2-last=Buchmann|editor2-first=Kurt|title=Fish parasites: pathobiology and protection|url=https://archive.org/details/fishparasitespat00woop|url-access=limited|date=2012|publisher=CABI|location=Wallingford, Oxfordshire|isbn=9781845938062|pages=[https://archive.org/details/fishparasitespat00woop/page/n83 73]–91|chapter=Chapter 5: Miamiensis avidus and related species}} Since 2022 there have also been several reports that scuticociliates might be responsible for mass die-off events of sea urchins across the world's oceans.{{cite news| last =Cummings| first =Sean| date = May 28, 2024| title = Mysterious sea urchin plague is spreading through the world’s oceans| newspaper = Science | page = | url =https://www.science.org/content/article/mysterious-sea-urchin-plague-spreading-through-world-s-oceans | access-date = June 17, 2024 | quote = }}