PHAGOTROPHIC FEEDING AND ITS IMPORTANCE TO THE LIFE CYCLE OF THE HOLOZOIC DINOFLAGELLATE, GYMNODINIUM FUNGIFORME1

Authors

  • Howard J. Spero,

    1. The Bellairs Research Institute, St. James, Barbados, West Indies
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    • 2

      New address: from 1 August 1981, Department of Biological Sciences, University of California, Santa Barbara, California 93106.

  • Montescue D. Morée

    1. Department of Oceanography, Texas A&M University, College Station, Texas 77843
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  • 1

    Accepted: 17 November 1980.

  • This research constitutes a portion of a thesis by H.J.S. to the Graduate College, Texas A&M University in partial fulfillment of the requirements for an M.Sc. He acknowledges the helpful suggestions made by the members of his committee, Drs. Thomas Bright, Elenor Cox, Rezneat Darnell and Jerry Neff. We thank Drs. Greta Fryxell, Lois Pfiester and F. J. R. Taylor for their critical reviews of the manuscript. This work was supported through funds provided by the Oceanography Department, Texas A&M University and Texas A&M mini-grant Project No. 15707.

ABSTRACT

The holozoic dinoflagellate, Gymnodinium fungiforme Anissimova, has been observed in both asexually and sexually reproducing cultures. Asexual reproduction is characterized by zoosporangium formation and subsequent new cell release. Sexuality is gametic, and planozygotes and hypnozygotes are present. The life cycle is highly dependent on feeding, and in food-depleted cultures the swimming cells rapidly disappear. These are replaced with resistant long-term resting cysts. Despite its small size (8.5–19 μm), G. fungiforme can feed on prey as large as the ciliated protozoan, Condylostoma magnum Spiegel (600–1000 μm in length), or small injured metazoans, and has been cultured phagotrophically with the chlorophyte, Dunaliella salina Teodoresco as a food source. Eleven additional species of algae including 1 chlorophyte, 7 chrysophytes and 3 rhodophytes, however, were not suitable as food sources. Feeding is characterized by the formation of ‘dynamic aggregations’ of hundreds of dinoflagellates that attach to the surface of a prey organism by a peduncle. G. fungiforme ingests the cytoplasm or body fluids of its prey and a feeding aggregation can ingest a C. magnum in 20–30 minutes.

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