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Download Chrysophyta--Golden brown algae Cells small
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simple unicellular naked flagellate Chrysophyta--Golden brown algae Cells small to medium (>10 microns) Nucleus (1), chloroplasts (2)brown to golden brown (chlorophyll a plus carotenoids), food stored mainly as oils and carbohydrates Unicellular or colonial, some species with flagellae (usually 2) Cell wall—often absent, sometimes present as a lorica (cellulose) Ochromonas Chromulina flagellate colonial form, a gelatinous matrix may be present but lorica absent--Uroglena Uroglena 50 microns large branched colonies, flagellate cells within a lorica--Dinobryon Ecology of Chrysophytes Common in the plankton of lakes especially during the colder parts of the year May occasionally form blooms that colour the water brown and give taste and odour problems—Eg Ochromonas Some species also found in cold steams and springs. Acid lakes and bogs, support a diverse Chrysophyte community, most important primary producers in such systems. Pyrrophyta--Dinoflagellates •Cells fairly large (>25 microns) •Nucleate (1), •Cellulose wall often present •Cells with grooves (sulci) within which flagellae lie •Chloroplasts, 2 or more small disc shaped, brown to golden brown (chlorophyll a, c, plus carotenoids), •Food stored as starch and oils •Cells often emitting bioluminescence •Cells very motile (8 mm/sec) cells without an armoured wall, but with a firm periplast with grooves for flagellae—Gymnodinium About 30-50 microns cells armoured, with a sculptured cellulose wall often consisting of several plates, perforated with pores, and with deep transverse and longitudinal grooves large (>100 microns) with lobe like extensions “horns”--Ceratium > 100 microns long cells armoured, with a sculptured cellulose wall often consisting of several plates, perforated with pores, and with deep transverse and longitudinal grooves, cells more or less spherical—Peridinium, Gonyaulax Mostly marine species Peridinium 40-60 microns Gonyaulax—causes red tides, shellfish poisoning in estuaries Cells about 25-30 microns Ecology of dinoflagellates Can be very important primary producers in both lakes and oceans Many dinoflagellates occur as symbionts inside animals eg corals or sponges Can cause toxic blooms, eg red tides, usually in estuaries—shellfish poisoning Very motile can usually maintain their position in the water column if they remain near the thermocline where turbulence is not too great Can produce bioluminescence in response to disturbance of the water column or predators. Many species are heterotrophic and mainly live by ingesting bacteria (phagocytosis), many such species have little chlorophyll.
