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SYNOPTIC DESCRIPTION OF THE PHYLUM EUGLENOIDA

SYNOPTIC DESCRIPTION OF THE PHYLUM EUGLENOIDA

EUKARYA> EXCAVATA> DISCICRISTATAE> EUGLENOIDA
EUGLENOIDA LINKS

Introduction

Hierarchical Classification

Description of this phylum comes from Bold and Wynne 1985; Dodge 1973; Grell 1976; Kudo 1966; Lee 1980; Lee et al. 1985; Margulis and Schwartz 1998; Sze 1986; Van Den Hoek et al. 1995; Graham and Wilcox 2000; Walne and Kivic 1990; Patterson (1999); Rosowski (2003); and Cavalier-Smith (2003).

I. SYNONYMS: Euglenophyta, Euglenozoa, euglenids.

II. NUMBER: 600 – >800 species.

III. PHYLUM CHARACTERISTICS:

  • A. Structure and Physiology:
    • Cell Form: Mainly motile unicells; some colonial.
    • Flagella: Two dissimilar flagella; 1 directed anteriorly (text with tooltip) An anteriorly-directed flagellum extends in the direction of the motion of the motile cell. The interpretation is that the flagellum functions by pulling the cell. and 1 directed posteriorly ( recurrent (text with tooltip) Recurrent flagella bend to the posterior end of the cell. Typically, they are identified as recurrent when anteriorly-directed flagella are present. ); usually anterior flagellum with a paraxial (text with tooltip) A paraxial rod is a stiffened rod-like structure that lies alongside the axoneme of one of the flagella in the Euglenidae. rod and delicate hairs.
    • Basal Bodies: Parallel (text with tooltip) Basal bodies are parallel when their orientation relative to each other is parallel. and inserted at the base of the reservoir (text with tooltip) A flagellar pocket is an invagination of the cell within which the flagellar insertions occur. Extensions of the flagellar pocket form the undulating membrane in trypanosomatids. This is sometimes called the reservoir, the crypt, the cytostome (inappropriately), or gullet. .
    • Cell Covering: Complex covering (= pellicle (text with tooltip) A pellicle is a complex outer cellular covering that occurs within the bounds of the plasmalemma. Often synonymous with the term theca, a pellicle defines such groups as the euglenoid-kinetoplastid clade amd the Kingdom Alveolatae. ) of sliding proteinaceous strips, twisted to form a reservoir (= gullet) at the anterior end and a point at the posterior end, particularly obvious in Euglena (Figure B). The pellicular strips (text with tooltip) Pellicular strips are proteinaceous strips that run the length of the cell and for the pellicle in the Euglenotista. The pellicular strips can slide past each other in certain euglenoids and thus produce the characteristic metaboly of certain of their cells. can slide past each other to provide a directed movement called metaboly, (note metaboly in Figures A&E).
    • Chloroplasts: When present, green with chlorophylls a and b; beta carotene; xanthophylls (text with tooltip) Xanthophyll is an oxygenated carotenoid secondary photosynthetic pigment that occurs in many of the photosynthetic eukaryotes. ; pyrenoid region; surrounded by a triple membrane.
    • Food Reserves: Paramylon (text with tooltip) Paramylon is a storage carbohydrate that is a polymer of glucose. It is in a class of compounds called glucans. It is found in euglenoids and haptophytes. , a polysaccharide; large, refractile and often with distinctive shapes; others with leucosin (text with tooltip) Chrysolaminarin (also called leucosin) is a storage carbohydrate that is a polymer of glucopyranoside units. Typically it is found in photosynthetic heterokonts. and lipid.
    • Mitochondria: Discoidal cristae (text with tooltip) Discoid cristae (crista, sing.) are swollen tube-like cristae within certain mitochondria. .
    • Golgi (text with tooltip) Golgi apparatus (also called dictyosome) is an internal membrane system of stacked flattened sacs. They occur in nearly all eukaryotes and are involved in storing and secreting cellular products. : Present.
    • Nucleus: Large, conspicuous with permanently condensed chromosomes; cells uninucleate.
    • Centrioles: Absent.
    • Inclusions and Ejectile Organelles: Eyespot (text with tooltip) An eyespot is a light-sensitive structure that does not form an image. This can be part of an organelle as in the chloroplast of certain microbial eukaryotes. It can be an elaborate structure that involves a light-sensitive swelling at the base of a flagellum (as in the euglenoids) or it can be a multicellular structure as in planarians. of red lipid-filled vesicles, associated with reservoir; light-sensitive swelling at base of large emergent flagellum.
    • No ejectile organelles.
  • B. Mitosis, Meiosis and Life History:
    • Mitosis: Nuclear membrane closed (text with tooltip) Mitosis is closed when the segregation of daughter chromosomes occurs within the bounds of the nuclear membrane (the nuclear membrane does not break down). ; internal spindle.
    • Meiosis: Not reported.
    • Sexual Reproduction and Life History: Some unconfirmed reports, but at least one account of a sexual cycle in Scytomonas. Cells often produce asexual cysts.
  • C. Ecology: Mainly freshwater; free-living, some epizoic; some photosynthetic, phagotrophic, and saprobic.
LITERATURE CITED

Baldauf, S. L. 2003a. The deep roots of eukaryotes. Science. 300 (5626): 1701-1703.

Bold, H. C. and M. J. Wynne. 1985. Introduction to the Algae. 2nd Edition. Prentice-Hall, Inc. Englewood Cliffs. NJ.

Bregalia, S. A., C. H. Slamovits, and B. S. Leander. 2007. Phylogeny of phagotrophic euglenids (Euglenozoa) as inferred from Hsp90 gene sequences. Journal of Eukaryotic Microbiology. 54(1): 86-92.

Busse, I. and A. Preisfeld. 2003. Systematics of primary osmotrophic euglenids: a molecular approach to the phylogeny of Distigma and Astasia (Euglenozoa). International Journal of Systematic and Evolutionary Microbiology. 53: 617-624.

Cavalier-Smith, T. 2003a. Protist phylogeny and the high-level classification of Protozoa. European Journal of Protistology. 39:338-348.

Dodge, J. D. 1973. The Fine Structure of Algal Cells. Academic Press. New York.

Graham, L. E., and L. W. Wilcox. 2000. Algae. Prentice Hall. Upper Saddle River, NJ.

Grell, K. G. 1973. Protozoology. Springer-Verlag. New York.

Kudo, R. R. 1966. Protozoology. 5th ed. Charles C. Thomas Publisher. Springfield.

Leander, B. S. 2008. Euglenida. euglenids or euglenoids. Version 11 September 2008. In: The Tree of Life Web Project, http://tolweb.org. http://tolweb.org/Euglenida/97461/2008.09.11.

Leander, B. S., R. E. Triemer, and M. A. Farmer. 2001. Character evolution in heterotrophic euglenids. European Journal of Protistology. 37: 337-356.

Lee, R. E. 1980. Phycology. Cambridge University Press. Cambridge.

Lee, J. J., S. H. Hunter, and E. C. Bovee, eds. 1985. An Illustrated Guide to the Protozoa. Society of Protozoologists. Lawrence, Kansas.

Linton, E. W. and R. E.Triemer. 2001. Reconstruction of the flagellar apparatus in Ploeotia costata (Euglenozoa) and its relationship to other euglenoid flagellar apparatuses. Journal of Eukaryotic Microbiology. 48(1): 88-94.

Margulis, L. and K. Schwartz. 1988. Five kingdoms, an illustrated guide to the phyla of life on earth. 2nd Edition. W.H. Freeman and Co. New York.

Margulis, L. and K. Schwartz. 1998. Five kingdoms, an illustrated guide to the phyla of life on earth. 3rd Edition. W. H. Freeman and Company. New York.

Mullner, A. N., D. G. Angeler, R. Samuel, E. W. Linton, and R. E. Triemer. 2001. Phylogenetic analysis of phagotrophic, phototrophic and osmotrophic euglenoids by using the nuclear 18S rDNA sequence. International Journal of Systematic and Evolutionary Microbiology. 51: 783-791.

Rosowski, J. R. 2003. Photosynthetic euglenoids. In: Wehr, J. D. and R. G. Sheath, eds. Freshwater Algae of North America. Chapter 10. Academic Press. New York. pp. 383-422.

Sze, P. 1986. A Biology of the Algae. Wm. C. Brown Publishers. Dubuque, Iowa.

Van Den Hoek, C., D. G. Mann, and H. M. Jahns. 1995. Algae, an introduction to phycology. Cambridge University Press. Cambridge.

Walne, P. L. and P. A. Kivic. 1990. Euglenida. In: Margulis, L., J.O. Corliss, M. Melkonian, and D.J. Chapman, eds. 1990. Handbook of the Protoctista; the structure, cultivation, habits and life histories of the eukaryotic microorganisms and their descendants exclusive of animals, plants and fungi. Jones and Bartlett Publishers. Boston. pp. 270-287.

Wenrich, D. H. 1924. Studies on Euglenamorpha hegneri n. g., n. sp., a euglenoid flagellate found in tadpoles. The Biological Bulletin. 47(3): 149-175.
By Jack R. Holt. Last revised: 02/18/2010
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