SYNOPTIC DESCRIPTION OF THE PHYLUM RAPHIDIOPHYTA (CHADEFAUD 1950)
| EUKARYA> CHROMALVEOLATA> HETEROKONTAE> RAPHIDIOPHYTA |
RAPHIDIOPHYTA LINKS
| This description comes from Margulis and Schwartz (1988 and 1998), Bold and Wynne (1985), Lee (1980), Kudo (1966), Grell (1976), Lee et al (1985), Heywood (1990), and Van den Hoek et al (1995). |
I. SYNONYMS: Chloromonads, raphidiophyceae.
II. NUMBER: 9 species (4 genera).
III. PHYLUM CHARACTERISTICS:
- A. Structure an Physiology
- Cell Form: Motile unicells.
- Flagella: Two flagella; posterior whiplash (text with tooltip) A whiplash flagellum is free of hair-like mastigonemes and usually is trailing or posteriorly-directed. ( 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. ) and anterior tinsel (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. with two rows of thick mastigonemes (text with tooltip) Mastigonemes are flagellar hairs. .
- 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. with rhizoplast (text with tooltip) A rhizoplast is a striated root system that extends from the basal body tinto the cell, usually to the nuclear envelope. .
- Cell Covering: Cell naked.
- 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. and c (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, 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. ; no 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. .
- Food Reserves: Oil.
- 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: Large with characteristic rhizoplast connecting it to the flagellar bases.
- Centrioles: Basal bodies (text with tooltip) Basal bodies (also called kinetosomes) are organelles that are not membrane-bound. All eukaryotic flagella (also called undulipodia) are underlain or attached to the cell by the basal body. The basal body is a microtubular structure with the general formula 9(3)+0. They are indistinguishable from centrioles. function as centrioles.
- Inclusions and Ejectile Organelles: Trichocysts (text with tooltip) Trichocysts are extrusosomes that also are characteristic of the ciliates and dinoflagellates. They can discharge and serve almost as an organelle equivalent to the nematocyst. However, their particular functions have yet to be defined to my satisfaction. or mucocysts (text with tooltip) A mucocyst (also called mucus body, muciferous body, mucus trichocyst) is an organelle or inclusion that extrudes mucus. .
- B. Mitosis, Meiosis and Life History
- Mitosis: Nuclear membrane breaks down at least a spindle poles; spindle microtubules originate from the flagellar bases; chromosomes with kinetochores (text with tooltip) A kinetochore is also called a centromere, the point on a chromosome to which the spindle fibers attach. .
- Meiosis: Not confirmed.
- Sexual Reproduction and Life History: Not confirmed.
- C. Ecology: Found in fresh water, brackish water, and marine plankton. Marine-brackish taxa bloom in organic rich water where they can cause fish kills. Gonyostomum has been known to increase and bloom in response to acid deposition.
| 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. 1986b. The kingdom Chromista: origin and systematics. In: F. E. Round and D. J. Chapman, eds. Progress in Phycological Research. BioPress Ltd. Bristol, UK. vol. 4, 309–347. Cavalier-Smith, T. and E. E. Chao. 1996. 18S rRNA sequence of Heterosigma carterae (Raphidiophyceae) and the phylogeny of heterokont algae (Ochrophyta). Phycologia. 35: 500-510. 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. Heywood, P. 1989. Some affinities of the Raphidiophyceae with other 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. 279-293. Heywood, P. 1990. Raphidiophyta. 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. 318-325. Heywood P. G. and F. Leedale. 2002. Order Raphidomonadida. In: J. J. Lee, G. F. Leedale, and P. Bradbury, eds. An Illustrated Guide to the Protozoa. 2nd edition. Society of Protozoologists. Lawrence, Kansas. USA. vol. 2. 744–751. Kudo, R.R. 1966. Protozoology. 5th ed. Charles C. Thomas Publisher. Springfield. 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. Lynn, D. H. and E. B. Small. 1990. Ciliophora. 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. 498-523. 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. Smith, G. M. 1950. The fresh-water algae of the United States. McGraw-Hill Book Co. New York. 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/ 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 |
