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SYNOPTIC DESCRIPTION OF THE PHYLUM XANTHOPHYTA

SYNOPTIC DESCRIPTION OF THE PHYLUM XANTHOPHYTA (ALLORGE EX FRITSCH 1935)

EUKARYA> CHROMALVEOLATA> HETEROKONTAE> XANTHOPHYTA
XANTHOPHYTA LINKS

Introduction

Hierarchical Classification

The following description of the phylum comes from Bold and Wynne (1985); Sze (1986); Lee (1980), Graham and Wilcox (2000), Margulis and Schwartz (1988 and 1998), Sleigh et al. (1984), Hibberd (1990), and Van den Hoek (1995).

I. SYNONYMS: Xanthophytes, yellow-green algae.

II. NUMBER: >650 species.

III. PHYLUM CHARACTERISTICS:

  • A. Structure and Physiology
    • Cell Form: Organisms filamentous, siphonous and coccoid.
    • Flagella: Two flagella; posterior whiplash and anterior tinsel with two rows of thick mastigonemes. Flagellar swelling at the base of the whiplash flagellum and associated with an eyespot.
    • Basal Bodies: Basal bodies perpendicular.
    • Cell Covering: Cell wall often of two overlapping halves or continuous.
    • Chloroplasts: Numerous yellow-green chloroplasts with chlorophylls a (text with tooltip) Chlorophyll A is a primary photosynthetic pigment of all photosynthetic eukaryotes (in the chloroplasts) and Cyanobacteria. It is membrane-bound on thyllakoids and absorbs mainly in the blue and red ranges of visible light. Its structure is that of a tetrapyrrole with a magnesium in the center. That is bound to a long aliphatic alcohol (phytol). Chlorophylls a, b, c, d, and e, together with the bacteriochlorophylls have similar structures and vary only in the structures of their side chains. , 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. ; also with B-carotene (text with tooltip) Carotenoids are accessory pigments that are fat-soluable. Generally orange, red, yellow, or brown, carotenoids come in two major classes: carotenes and xanthophylls. , 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. ; 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. situated within the chloroplast.
    • Food Reserves: Oil or fat.
    • 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: Haploid; outer membrane bound to one of the discoid chloroplasts.
    • Centrioles: Present.
    • Inclusions and Ejectile Organelles: Not present.
  • B. Mitosis, Meiosis and Life History
    • Mitosis: Mitosis closed with intranuclear spindle (text with tooltip) An intranuclear spindle elaborates within the nuclear membrane of an organism with closed mitosis. and centrioles (text with tooltip) The centriole duplicates at the onset of mitosis or meiosis in animals and some other taxa. It then serves as the organizing center from which the microtubular spindle fibers develop and lead the chromosomes apart during nuclear division. Curiously, the centriole also seems to be identical to basal bodies, the organizing structure from which the array of microtubules emerge to form the eukaryotic flagellum. outside of the nuclear membrane, opposite the poles.
    • Meiosis: Present.
    • Sexual Reproduction and Life History: Haploid with biflagellated gametes; isogamous (text with tooltip) Isogamous (adj) describes sexual reproduction in which the gametes are structurally identical. , anisogamous (text with tooltip) Anisogamous (adj.) describes sexual reproduction in which the gametes are structurally siimilar, but not identical. or oogamous.
  • C. Ecology: Mainly found in fresh water.
LITERATURE CITED

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

Beakes, G. W. 1989. Oomycete Fungi: their phylogeny and relationship to chromophyte algae. 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. 325-342.

Bold, H. C., C. J. Alexopoulos, and T. Delevoryas. 1987. Morphology of Plants and Fungi. 5th Edition. HarperCollins Publishers, Inc. New York.

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

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.

Hibberd, D. J. 1990a. Xanthophyta. 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. 686-697.

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

Lee, R. E. 1995. Phycology. 2nd Edition. Cambridge University Press. Cambridge.

Lee, R. E. 1999, Phycology: 3rd ed., CambridgeUniversity Press, Cambridge, UK.

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

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

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.

Scagel, R.F., R.J. Bandoni, J.R. Maze, G.E. Rouse, W.B. Schofield, and J.R. Stein. 1982. Nonvascular Plants. Wadsworth Publishing Co., Belmont, California.

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.

Van Den Hoek, C., D. G. Mann, and H. M. Jahns. 1995. Algae, an introduction to phycology. Cambridge University Press. Cambridge.
By Jack R. Holt. Last revised: 02/28/2012
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