Dinoflagellates (Class: Dinophyceaea)

Dinoflagellates

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Dinoflagellates are unicellular and very abundant next to diatoms. They have characteristics of both plants and animals. Like plants, they prepare  their food materials by converting  sunlight and nutrients in water into food and however, like animals, many varieties of dinoflagellates eat microscopic particles  of organic matter found in the water. Some dinoflagellates even eat each other, the condition of which is known as phagotrophy.  They have two whip-like appendages, called flagella, which provide some mobility. They lack an external skeleton of silicon but are impregnated with armored plates of the carbohydrate, cellulose.  These generally small organisms  usually solitary and rarely chain forming ones  They reproduce by simple fission, as  the diatoms.  Each daughter cell of diatom retains half the original cellulose armor and forms a new part to replace the missing half without any reduction in size; hence, successive generations do not change in size.  Some dinoflagellates are also capable of producing toxins that are released into seawater.  At times, dinoflagellates become extremely abundant, the condition is known as  bloom (2-8 million cells per liter), and  the toxins released by these forms may affect other organisms of higher trophic levels, causing mass mortality.  Such extreme concentrations, or blooms of dinoflagellates are called red tides and are responsible for massive localized mortality in fishes in various places. 

          Some dinoflagellates have non-motile stages called Zooxanthellae, which are symbionts in the tissues of many invertebrates such as corals, sea anemones, and giant clams.  The dinoflagellate species like Noctiluca scintillans is highly bioluminescent.   

Last modified: Wednesday, 21 March 2012, 5:39 AM