Euglena

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Euglena

[yü′glē·nə]
(biology)
A genus of organisms with one or two flagella, chromatophores in most species, and a generally elongate, spindle-shaped body; classified as algae by botanists (Euglenophyta) and as protozoans by zoologists (Euglenida).
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Euglena

 

a genus of microscopic motile single-celled organisms of the division Euglenophyta. The cell is spindle- or ribbon-shaped, with a pellicle in front, a single external flagellum, and a stigma next to the gullet. The ocellus is red. The chloroplasts are green and frequently complex in structure.

About 60 species of euglenas are known. They mainly inhabit shallow bodies of water, where they swim at any depth. Some species, such as Euglena viridis, can discard the flagellum and creep or, after taking on a spherical form, live immobile on the surface of the water, silt, or soil. Under unfavorable conditions they become transformed into spores. Nutrition is usually myxotrophic, or if there is a loss of chlorophyll, saprophytic. The organisms are distributed widely and sometimes cause the coloration of waters. Euglena sanguinea, which is rich in carotene, makes water red. Euglenas are used in laboratory experiments.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Organic matter and iron are implicated to be among the ecological factors that affect the euglenoids [51].
Phylum 3 Discomitochondria (Mastigotes, Zoomastigotes, "Zooflagellates," Unicells with Discoid Cristae, Euglenoids, Kinetoplastids, Mastigote Amebas)
Ultrastructure and molecular sequence similiarities demonstrate that chlorophylls a + b containing green algae (except for photosynthetic euglenoids) share a unique evolutionary history with multicellular green plants.
Certain assemblages are thus referred to as oligotrophic species (desmids, chrysophytes, diatoms) or eutrophic indicators (cyanobacteria, euglenoids) (Reynolds 1998).
Pigment Algal group Chl a all algae Chl b chlorophytes Chl c chrysophytes, diatoms, dinoflagellates [Beta]-carotene all algae Alloxanthin cryptophytes Diatoxantbin diatoms, few chrysophytes Fucoxanthin chrysophytes, diatoms, some dinoflagellates Lutein chlorophytes, euglenoids Zeaxanthin cyanobacteria Oscillaxanthin(*) filamentous cyanobacteria Peridinin dinoflagellates * Includes oscillaxanthin, 4-keto-myxoxanthophyll, and aphanizophyll.
Until now, both of the EF phylogenies (EF-1 alpha tree is shown in [ILLUSTRATION FOR FIGURE 1 OMITTED]) clearly and consistently suggested (a) that three amitochondriate protists, Glugea plecoglossi (microsporidian), Giardia lamblia (diplomonad), and Trichomonas tenax (trichomonad), represent an early-branching eukaryotic group; and that among them, the divergence of Glugea seems to be the earliest (1-5); and (b) that another amitochondrial protist, Entamoeba histolytica, is likely to have diverged after the divergences of some mitochondrion-containing protists, but is not likely to have diverged later than euglenoids, as suggested by the SrRNA tree (6).