Phaeocystis globosa (Prymnesiophytes, Phaeocystaceae), diameter 480 µm, Sylt 10.2015. 0:20 min. Phaeocystis globosa is the most important species of Prymnesiophytes in the North Sea. This species occurs as single motile flagellate form and may also develop blooms (palmella form, colonies with a size up to some cm) which may influence development of bentic fish and other organisms because of anoxic conditions as a result of such blooms. Video can be used for teaching.