cyanobacterial morphology cyanobacterial morphology cyanobacterial morphology refers to the form or shape of cyanobacteria. cyanobacteria are a large and diverse phylum of bacteria defined by their unique combination of pigments and their ability to perform oxygenic photosynthesis. different forms of cyanobacteria (a) spherical and ovoid unicellular, (b) colonial, (c) filamentous, (d) spiral, (e) unsheathed trichome, (f) sheathed trichome, (g) false branching, (h) true branching, (i) different cell types in filamentous cyanobacteria. cyanobacteria often live in colonial aggregates that can take a multitude of forms. of particular interest among the many species of cyanobacteria are those that live colonially in elongate hair-like structures, known as trichomes. these filamentous species can contain hundreds to thousands of cells. they often dominate the upper layers of microbial mats found in extreme environments such as hot springs, hypersaline water, deserts and polar regions, as well as being widely distributed in more mundane environments. many filamentous species are also motile, gliding along their long axis, and displaying photomovement by which a trichome modulates its gliding according to the incident light. the latter has been found to play an important role in guiding the trichomes to optimal lighting conditions, which can either inhibit the cells if the incident light is too weak, or damage the cells if too strong. overview