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SYNOPTIC DESCRIPTION OF THE PHYLUM SILICOFLAGELLATA

SYNOPTIC DESCRIPTION OF THE PHYLUM SILICOFLAGELLATA (BORGERT 1890)

EUKARYA> CHROMALVEOLATA> HETEROKONTAE> SILICOFLAGELLATA
SILICOFLAGELLATA LINKS

Introduction

Hierarchical Classification

The following description comes from Adl et al. (2005), Margulis and Schwartz (1988 and 1998), Kudo (1966), Grell (1976), Kristiansen (1982, cited in Bold and Wynne, 1985), and Kristiansen (1990).

I. SYNONYMS: Silicoflagellates, dictyophytes, pelagiophytes.

II. NUMBER: number of taxa difficult to determine because of species variability (120 genera).

III. PHYLUM CHARACTERISTICS:

  • A. Structure and Physiology
    • Cell Form: Coccoid, amoeboid, filamentous, colonial, or thalloid, usually flagellated.
    • Flagella: One or two flagella; 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. whiplash (text with tooltip) (1) A whiplash flagellum is a eukaryotic 9+2 flagellum with few or no flagellar hairs or scales. These may be directed anteriorly or posteriorly. (2) A whiplash flagellum is free of hair-like mastigonemes and usually is trailing or posteriorly-directed. and anterior (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. tinsel (text with tooltip) A tinsel flagellum is one that is covered with flagellar hairs and thus appears thicker in light microscopy. Usually, tinsel flagella are anteriorally-directed. with two rows of thick mastigonemes (text with tooltip) Mastigonemes are flagellar hairs. . These do not have a flagellar swelling or eyespot. The pelagiophytes have bipartite tubular hairs on the anterior flagellum, dictyophytes have the typical tripartite hairs. Some flagella have paraflagellar rods.
    • Basal Bodies: Basal bodies perpendicular (text with tooltip) Basal bodies are perpendicular (or orthogonal) when their orientation relative to each other is at a right angle. . Basal bodies in contact with nucleus in some taxa.
    • Cell Covering: Usually naked but may be covered by cellulosic wall, scales (text with tooltip) Protist scales are regular overlapping structures on the outside of the cell. They may be organic, silicaceous, or carbonaceous and may serve as an articulated cell wall. Scales may occur on the cells of a range of unrelated taxa. , or a delicate lorica (text with tooltip) A lorica is a covering that occurs outside of the cell membrane. It is secreted by the cell and usually is organic. Loricas do not completely enclose the cell. Periplasts, structures similar to loricas do enclose the cell. Lorica stands for armour. . Some taxa make skeletons of silica.
    • Chloroplasts: Variable; one to many golden brown with chlorophylls a and c1 and c2 (text with tooltip) Chlorophyll C is a variant of Chlorophyll A. and a secondary photosynthetic pigment in the many of the photosynthetic heterokonts and dinoflagellates. , they also have chlorophyll c3. With β-carotene, fucoxanthin (text with tooltip) Fucoxanthin is a carotenoid secondary photosynthetic pigment that occurs in many of the photosynthetic eukaryotes like the heterokonts and haptotists. and other xanthophylls (text with tooltip) Xanthophyll is an oxygenated carotenoid secondary photosynthetic pigment that occurs in many of the photosynthetic eukaryotes. ; 3 thylakoids in the photosynthetic lamellae. The chloroplast genome is
    • Food Reserves: Chrysolaminarin (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 fat; some phagotrophic.
    • Mitochondria: Tubular cristae (text with tooltip) Mitochondrial cristae that form as extended saccate structures or tubes are called tubular cristae. .
    • 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: Usually haploid? Outer membrane may be confluent with membranes of other organelles or in contact with a basal body.
    • Centrioles: Basal bodies function as centrioles.
    • Inclusions and Ejectile Organelles: Phagotrophic forms with food vacuoles.
  • B. Mitosis, Meiosis and Life History
    • Mitosis: Nuclear membrane breaks down at least a spindle poles.
    • Meiosis: Present.
    • Sexual Reproduction and Life History: Most taxa alternate between motile and nonmotile stages. Likely, this alternation reflects stages in a sexual life history.
  • C. Ecology: Mainly found in marine environments.
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.

Cavalier-Smith, T. 1989. The Kingdom Chromista. In: Green, J.C., B.S.C. Leadbeater, and W.L. Diver, eds. The Chromophyte Algae: Problems and Perspectives. Systematics Association Special Volume No. 38. Clarendon Press. Oxford. pp. 381-407.

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

Kristiansen, J. 1990. Chrysophyta. 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. 438-453.

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

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

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

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.

Patterson, D. J. 1989. Stramenopiles: chromophytes from a protistan perspective. In: Green, J. C., B. S. C. Leadbeater, and W. L. Diver, eds. The chromophyte algae, problems and perspectives. Systematics Association Special Volume No. 38. Clarendon Press. Oxford. pp. 357-379.

Patterson, D. J. 1999. The diversity of eukaryotes. American Naturalist. 154 (Suppl.): S96–S124.

Sleigh, M.A., J.D. Dodge and D.J. Patterson. 1984. Kingdom Protista. In: Barnes, R.K.S., ed. A Synoptic Classification of Living Organisms. Sinauer Associates, Inc. Sunderland, Mass.

Sogin, M. L. and D. J. Patterson. 1995. Stramenopiles. Version 01 January 1995 (under construction). http://tolweb.org/Stramenopiles/2380/1995.01.01 In: The Tree of Life Web Project, http://tolweb.org/

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

Taylor, F. J. R. 1976. Flagellate Phylogeny: A Study in Conflicts. J. Protozool. 23: 28-40.
By Jack R. Holt. Last revised: 02/26/2012
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