portrait

Description:

Portrait Synura uvella (Ehrenberg,1835), a colonial chrysophyte flagellate. Colonies are spherical or cylindrical, composed of pyriform cells attached by their posterior ends.The cells of this colony have loosened slightly from one another. Species identification is based on ultrastructure of silica scales on the cell surface (giving the surface of these cells a serrated appearance). Scales originate in cytoplasmic vesicles and are extruded to the cell exterior. Several different types of scales occur on an individual cell. Cells have two subequal flagella, one hairy and the other smooth on electron microscopy. Two yellow-brown chloroplasts flank a central nucleus. A contractile vacuole is seen posterior to the large chrysolaminarian vacuole in these cells. Although a stigma is absent, colonies are phototrophic, a basal flagellar swelling acting as photoreceptor. Red droplets in the anterior end of cells, not associated with chloroplasts may be mistaken for stigmata. Multiple contractile vacuoles may be present, usually located posteriorly. From freshwater pond near Boise, Idaho. DIC.