Editing Rotifer (section)

== Taxonomy and naming ==
{{See also|List of bilaterial animal orders}}

[[John Harris (writer)|John Harris]] first described the rotifers (in particular a [[Bdelloidea|bdelloid rotifer]]) in 1696 as "an animal like a large [[maggot]] which could contract itself into a spherical figure and then stretch itself out again; the end of its tail appeared with a forceps like that of an [[earwig]]".<ref name="cambridge1896"/> In 1702, [[Antonie van Leeuwenhoek]] gave a detailed description of ''[[Rotaria rotatoria|Rotifer vulgaris]]'' and subsequently described ''[[Floscularia ringens|Melicerta ringens]]'' and other species.<ref name="brit1907">{{cite book | title = Encyclopædia Britannica | edition = Ninth | year = 1907 | pages = 8 | volume = XXI | author = Bourne, A.G. | editor = Baynes, Spencer and W. Robertson Smith | publisher = The Werner Company | location = Akron, Ohio | url = https://books.google.com/books?id=yAsEAAAAYAAJ}}</ref> He was also the first to publish observations of the revivification of certain species after drying. Other forms were described by other observers, but it was not until the publication of [[Christian Gottfried Ehrenberg]]'s {{lang|de|Die Infusionsthierchen als vollkommene Organismen}} in 1838 that the rotifers were recognized as being [[multicellular]] animals.<ref name="brit1907"/>

In the landmark monograph on ''The Rotifera'' (1886-9) by [[Charles Thomas Hudson|C.T. Hudson]], assisted by [[Philip Henry Gosse|P.H. Gosse]],<ref>Charles Thomas Hudson, ''The Rotifera; or Wheel-Animalcules.'' Assisted by P.H. Gosse, [https://books.google.com/books?id=Lt5L5lxgpDIC&pg=RA1-PA5&dq=charles+thomas+hudson,+%22the+rotifera%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwjzg57h5ZSMAxXUv4kEHeAKCIoQ6AF6BAgMEAM#v=onepage&q=charles%20thomas%20hudson%2C%20%22the%20rotifera%22&f=fa volume 1] and [https://books.google.com/books?id=9dsgDrxr-NIC&pg=PP196&dq=charles+thomas+hudson,+%22the+rotifera%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwjzg57h5ZSMAxXUv4kEHeAKCIoQ6AF6BAgNEAM#v=onepage&q=charles%20thomas%20hudson%2C%20%22the%20rotifera%22&f=fals volume 2], 1886; Hudson and Gosse, ''[https://books.google.com/books?id=PZ5aAAAAQAAJ&printsec=frontcover&dq=charles+thomas+hudson,+%22the+rotifera%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwjzg57h5ZSMAxXUv4kEHeAKCIoQ6AF6BAgOEAM#v=onepage&q=charles%20thomas%20hudson%2C%20%22the%20rotifer The Rotifera; or Wheel-Animalcules, both British and Foreign. Supplement with illustrations].'' Assisted by P.H. Gosse, 1889.</ref> 400 British and foreign species were included; by 1912, the total reached 607 species.<ref>Wertheimer, Douglas (2024), ''[https://search.worldcat.org/title/1495001167 Philip Henry Gosse: A Biography],'' Glasgow: Brethren Archivists and Historians Network, p.575 fn.250.</ref> About 2,200 [[species]] of rotifers have now been described. Their taxonomy is currently in a state of flux. One treatment places them in the phylum Rotifera, with three classes: [[Seisonidea]], [[Bdelloidea]] and [[Monogononta]].<ref>{{Citation |last1=Barnes |first1=R.S.K. |last2=Calow |first2=P. |last3=Olive |first3=P.J.W. |last4=Golding |first4=D.W. |last5=Spicer |first5=J.I. |year=2001 |title=The Invertebrates: a synthesis |location=Oxford; Malden, MA |publisher=Blackwell |isbn=978-0-632-04761-1 |name-list-style=amp }}, p. 98</ref> The largest group is the Monogononta, with about 1,500 species, followed by the Bdelloidea, with about 350 species. There are only two known genera with three species of Seisonidea.<ref name="Berkeley">{{cite web | url = http://www.ucmp.berkeley.edu/phyla/rotifera/rotifera.html | title = Introduction to the Rotifera | access-date = 2008-07-27 | date = 1 May 2000 |author1=Baqai, Aisha |author2=Guruswamy, Vivek |author3=Liu, Janie |author4=Rizki, Gizem |name-list-style=amp | publisher = University of California Museum of Paleontology}}</ref>

The [[Acanthocephala]], previously considered to be a separate phylum, have been demonstrated to be modified rotifers. The exact relationship to other members of the phylum has not yet been resolved.<ref name="shimek">{{cite web | url = http://reefkeeping.com/issues/2006-01/rs/index.php | author = Shimek, Ronald | access-date = 2008-07-27 | title = Nano-Animals, Part I: Rotifers | publisher = Reefkeeping.com |date=January 2006 }}</ref> One possibility is that the Acanthocephala are closer to the Bdelloidea and Monogononta than to the Seisonidea; the corresponding names and relationships are shown in the [[cladogram]] below.

{{clade|style=line-height:100%
|1={{clade
|label1=[[Syndermata]]
|1={{clade
   |1=[[Seisonida]]
   |2={{clade
   |label1=[[Eurotatoria]]
   |1={{clade
   |1=[[Bdelloidea]]
   |2=[[Monogononta]]
  }}
   |2=[[Acanthocephala]]
   }}
 }}
}}
}}

The Rotifera, strictly speaking, are confined to the Bdelloidea and the Monogononta. Rotifera, Acanthocephala and Seisonida make up a [[clade]] called Syndermata.<ref>{{Citation |last1=Ruppert |first1=Edward E. |last2=Fox |first2=Richard S |last3=Barnes |first3=Robert D. |year=2004 |title=Invertebrate zoology : a functional evolutionary approach |edition=7th |location=Belmont, CA |publisher=Thomson-Brooks/Cole |isbn=978-0-03-025982-1 |name-list-style=amp |url-access=registration |url=https://archive.org/details/isbn_9780030259821 }}, p. 788ff. – see particularly p. 804</ref>

=== Etymology ===
The word ''[[wikt:rotifer|rotifer]]'' is derived from a [[Neo-Latin]] word meaning '[[wheel]]-bearer'<ref>{{cite book |title=Biology of the invertebrates |last=Pechenik |first=Jan A.|year=2005 |publisher=McGraw-Hill, Higher Education |location=Boston |isbn=978-0-07-234899-6|pages=178}}</ref> due to the corona around the mouth that in concerted sequential motion resembles a wheel (although the organ does not actually rotate).