Dinoflagellates

Abstract

Dinoflagellates are marine or freshwater, photosynthetic or nonphotosynthetic protists that swim by two dissimilar flagella, usually present on the side; one is ribbon‐like, winding around to the cell's left, and the other trails behind. Most dinoflagellates have an unusual nucleus, the dinokaryon, throughout their life cycle. Cells are naked or have a theca consisting of cellulose plates lying under the cell membrane; resting cysts have a tough dinosporin wall, which can fossilize readily.

Keywords: dinoflagellata; flagellates; dinozoa; pyrrhophyta; alveolata

Figure 1.

Flagellar arrangements in dinoflagellates. (a) Anterior insertion, found in prorocentroids. (b) The typical flagellar arrangement in dinoflagellates, with both flagellae arising from the ventral side and the transverse flagellum winding to the cell's left (redrawn from Taylor, ).

Figure 2.

A detail of the transverse flagellum, showing its wavy, ribbon‐like form (from Gaines and Taylor, ).

Figure 3.

A diagrammatic cross‐section of a dinoflagellate, showing the internal organization. Note the single layer of amphiesmal vesicles lying beneath the cell membrane, the prominent nucleus with condensed chromosomes and the pusular cavities (redrawn from Taylor, ).

Figure 4.

Torsion at its extreme in Cochlodinium.

Figure 5.

Polykrikos, which resembles a fused state in which the number of nuclei in the single cellular compartment is half the number of external flagella pairs and girdles.

Figure 7.

The basic dinoflagellate life cycle. (1) The asexual phase of repeated divisions of the haploid swimming cell (mastigote). (2) Formation of a temporary cyst from a single cell shedding its theca (not in all dinoflagellates). (3) The sexual cycle, involving the fusion of gametes resembling normal cells, a swimming zygote, encystment to produce a dormant resting cyst with a tough wall (not in all dinoflagellates) and meiosis after excystment.

Figure 8.

Scanning electron micrograph (SEM) of K. micrum, an athecate dinoflagellate, showing the two flagella, the transverse lying in the girdle depression, the longitudinal arising from the sulcus. The episome is anterior to the girdle and the hyposome is the part posterior to the girdle, cell diameter 8 μm. The small objects in the background are bacteria.

Figure 6.

SEM of the cellulose theca of Lingulodinium polyedra. Most of the plate boundaries are marked by ridges. The apical plates are gaping slightly. The plates are densely pored, cell diameter 60 μm.

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References

Fensome RA, Taylor FJR, Norris G et al. (1993) A classification of living and fossil dinoflagellates. Micropaleontology (Special Publication) 7: 351pp.

Gaines G and Taylor FJR (1985) Form and function of the dinoflagellate transverse flagellum. Journal of Protozoology 32: 290–296.

Spector DL (ed.) (1984) Dinoflagellates, 545pp. New York: Academic Press.

Taylor FJR (1980) On dinoflagellate evolution. BioSystems 13: 65–108.

Taylor FJR (1987) The Biology of Dinoflagellates, 85pp. Oxford: Blackwell Scientific Publishers.

Further Reading

Dodge JD (1989) Phylogenetic relationships of dinoflagellates and their plastids. In: The Chromophyte Algae: problems and perspectives. Green JC, Leadbeater BSC and Diver WL (eds). Special vol. 38, chap. 11, pp. 207–227. Oxford: The Systematics Association.

Evitt WR (1985) Sporopollenin dinoflagellate cysts: Their morphology and interpretation. American Association of Strategic Palynologists, Monographic Series. 1: 1–333.

Sarjeant WAS (1974) Fossil and Living Dinoflagellates, 182pp. London: Academic Press.

Soyer‐Gobillard M‐O and Moreau H (2000) Dinoflagellates. Encyclopedia of Microbiology, 2nd edn, vol. 2, pp. 42–54. New York: Academic Press.

Taylor FJR (1989) Phylum dinoflagellata, Chap. 24, 419–437. In: Margulis L, Corliss JO, Melkonian M and Chapman, DJ (eds) Handbook of the Protoctista. 914pp, Boston: Jones and Barlett.

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How to Cite close
Taylor, FJR(Jan 2006) Dinoflagellates. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0001977]