opalinid

opalinid

      (subphylum Opalinata), any of about 150 protozoans found in the intestinal tracts of amphibians and some other animals. The nuclei of opalinids vary in number from two (e.g., Zelleriella) to many (e.g., Cepedea); the locomotor organelles (short, hairlike projections) are arranged in slanting, longitudinal rows. Species of the genus Opalina range from 90 to 500 micrometres in length. Reproduction is sexual by fusion of gametes (syngamy) or asexual by longitudinal splitting with distribution of the nuclei. Opalinids inhabit the intestines of amphibians (e.g., salamanders, newts) and some reptiles and fishes. They do not harm their host. Distribution is by encystment after reproduction; the cyst escapes in host feces and is ingested by another host. Opalinids are found worldwide, although species vary with location. One species, Zelleriella opisthocarya, is itself parasitized by another protozoan, Entamoeba paulista.

      The taxonomic position of opalinids is uncertain, and they have been variously classified. Formerly considered a separate group, they were called Protociliata, but any close relationship to contemporary ciliate groups is now considered doubtful.

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Universalium. 2010.

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Look at other dictionaries:

  • opalinid — opa·lin·id (o″pə linґid) 1. pertaining or referring to protozoa of the subphylum Opalinata. 2. any protozoan of the subphylum Opalinata …   Medical dictionary

  • opalinid — opa·linid …   English syllables

  • opalinid — I. |ōpə|līnə̇d, lēn , lin adjective Etymology: New Latin Opalinidae, family of protociliates, from Opalina, type genus + idae : of or relating to the genus Opalina or the family Opalinidae II. noun ( s) Etymology …   Useful english dictionary

  • Opalinidae — For other uses, see Opaline (disambiguation). Opalinidae Scientific classification Kingdom: Chromalveolata Division: Heterokontophyta Class …   Wikipedia

  • Opalinida — Taxobox color = greenyellow name = Opalinida image width = 300px image caption = domain = Eukaryota regnum = Chromalveolata divisio = Heterokontophyta classis = Opalinea ordo = Opalinida subdivision ranks = Genera subdivision = Opalina… …   Wikipedia

  • Gastrophryninae — Gastrophryninae …   Wikipédia en Français

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