Flagellate

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Not to be confused with flagellation or fellate.
This article is about eukaryotic flagellates. For bacterial flaggella and their differences, see Flagellum.
"Flagellata" from Encyclopædia Britannica
"Flagellata" from Ernst Haeckel's Artforms of Nature, 1904
Parasitic excavate (Giardia lamblia)
Green alga (Chlamydomonas)

A flagellate is an organism with one or more whip-like organelles called flagella. Some cells in animals may be flagellate, for instance the spermatozoa of most phyla. Flowering plants do not produce flagellate cells, but ferns, mosses, green algae, some gymnosperms and other closely related plants do. Likewise, most fungi do not produce cells with flagellae, but the primitive fungal chytrids do. Many protists take the form of single-celled flagellates.

The word flagellate describes a particular construction characteristic of many eukaryotic organisms and their means of motion. The term does not imply any specific relationship or classification of the organisms that possess flagellae. However, the term "flagellate" is included in other terms (such as "dinoflagellate" and "zooflagellate") which often are more formally characterized.[1]

Form and behavior[edit]

Eukaryotic flagella are supported by microtubules in a characteristic arrangement, with nine fused pairs surrounding two central singlets. These arise from a basal body. In some flagellates, flagella direct food into a cytostome or mouth, where food is ingested. Flagella often support hairs, called mastigonemes, or contain rods. Their ultrastructure plays an important role in classifying eukaryotes.

Among protoctists and microscopic animals, a flagellate is an organism with one or more whip-like organelles called flagella. Some cells in animals may be flagellate, for instance the spermatozoa of most phyla. Flowering plants do not produce flagellate cells, but ferns, mosses, green algae, and some gymnosperms and closely related plants do so. Likewise, most fungi do not produce cells with flagellae, but the primitive fungal chytrids do. Many protists take the form of single-celled flagellates.

Flagella are generally used for propulsion. They may also be used to create a current that brings in food. In most things, one or more flagella are located at or near the anterior of the cell e.g. Euglena. Often there is one directed forwards and one trailing behind. Among animals, fungi, and Choanozoa, which make up a group called the opisthokonts, there is a single posterior flagellum. They are from the phylum Mastigophora. They can cause diseases and they can make their own food. They reproduce by binary fission.They spend most of their existence moving or feeding. Many parasites that affect human health or economy are flagellates. Flagellates are the major consumers of primary and secondary production in aquatic ecosystems - consuming bacteria and other protists.

Flagellata or Mastigophora[edit]

In older classifications, some protozoa were grouped in Flagellata (or Mastigophora), sometimes divided in Phytoflagellata (Phytomastigina) and Zooflagellata (Zoomastigina). They were sometimes grouped with Sarcodina (ameboids) in Sarcomastigophora.

Modern classifications place these example genera into the following groups (see Kudo system):

Genera Classification Older classification
Multicilia, Mastigamoeba, Phalansterium Amoebozoa Zoomastigina
Ancyromonas Apusozoa Zoomastigina
Cercomonas Rhizaria Zoomastigina
Trypanosoma, Bodo, Oxymonas, Giardia, Trichomonas Excavata Zoomastigina
Bicosoeca Chromalveolata > Heterokontophyta > Bicosoecea Zoomastigina
Salpingoeca, Codosiga Opisthokonta > Choanoflagellata Zoomastigina
Cryptomonas Chromalveolata > Cryptophyta Phytomastigina
Pontosphaera Chromalveolata > Haptophyta Phytomastigina
Chromulina, Synura Chromalveolata > Heterokontophyta Phytomastigina
Prorocentrum, Peridinium Chromalveolata > Alveolata > Dinophyta Phytomastigina
Chlamydomonas, Volvox, Nephroselmis Archaeplastida > Viridiplantae > Chlorophyta Phytomastigina
Euglena Excavata > Euglenozoa Phytomastigina

References[edit]

  1. ^ Cavalier-Smith T. (1995). "Zooflagellate phylogeny and classification". Tsitologiia 37 (11): 1010–29. PMID 8868448. 

External links[edit]

  • Flagellata at the US National Library of Medicine Medical Subject Headings (MeSH)
  • The Flagellates. Unity, diversity and evolution. Ed.: Barry S. C. Leadbeater and J. C. Green Taylor and Francis, London 2000.