portrait

Description:

Asterococcus (a-stir-owe-cock-us) superbus. The large round or ellipsoid cells of Asterococcus occur singly or in groups with up to 8 cells embedded in a well-developed mucilage envelope. Groups reach 180 microns in diameter. The gelatinous sheaths are normally colourless and in concentrically arranged layers. The sheaths may be coloured brown by iron hydroxide. The single chloroplast is star-shaped and the pyrenoids are arranged in the center of the cell. The nucleus is located in a gap between the strands of the chlororoplast, together with two contractile vacuoles. No eyespot. Common in freshwater ponds and lakes. This image is of a squashed colony of Asterococcus superbus. The concentrically arranged layers of the gelatinous sheaths are clearly visible. The cells measuring 22 - 26 microns in diameter. Differential interference contrast.