Article
Article
Hymenostomatida
Article By:
Corliss, John O. Department of Zoology, University of Maryland, College Park, Maryland.
Last reviewed:January 2020
DOI:https://doi.org/10.1036/1097-8542.331800
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- Hymenostomatida, published June 2014:Download PDF
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An order of ciliated protozoans. The order Hymenostomatida belongs to the protozoan class Oligohymenophorea (phylum Ciliophora) and contains many species that often are of small size and fairly uniform ciliation. Primarily, the members of the order Hymenostomatida (hymenostomes; see illustration) are of importance as the first possessors of a definite, though inconspicuous, buccal ciliature. This ciliature consists of an undulating membrane on the right side of the buccal cavity and an adoral zone of membranelles that is primitively composed of three membranelles on the left side. This tetrahymenal, or four-part, buccal ciliary apparatus is considered the fundamental condition from which the oral ciliature of many subsequent higher groups evolved. See also: Cilia and flagella; Ciliophora; Protozoa
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