Entodiniomorphida

Article By:

Corliss, John O. Department of Zoology, University of Maryland, College Park, Maryland.

Last reviewed:2012

DOI:https://doi.org/10.1036/1097-8542.235000

An order of the Spirotrichia. These are strikingly different-looking ciliates, covered with a smooth, firm pellicle. They are devoid of external ciliature except for the adoral zone of membranelles and, occasionally, one or two other tufts or zones of other specialized cilia. Internal organization of the body is very specialized and complex. These organisms are considered to be highly evolved. Entodiniomorphids occur exclusively as endocommensals of herbivorous mammals, either in the rumen and reticulum of ruminants or in the colon of certain higher mammals. The ophryoscolecids, which comprise the majority of species in this order, are found in fantastic abundance in their hosts; for example, there have been estimations of as many as 10 billion per cow. Herbivores can survive free of their harmless protozoan guests, but the reverse is not true. Epidinium, Ophryoscolex (see illustration), and Entodinium occur in ruminants. Troglodytella is found in the colon of anthropoid apes. See also: Ciliophora; Protozoa

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