Oscillatoria animalis cyanobacteria, dark field light micrograph. The genus name for this cyanobacterium comes from the movement it makes as it orientates itself to the brightest light source available, from which it gains energy by photosynthesis. The red colouration is caused by autofluorescence of several photosynthetic pigments and light-harvesting proteins. Each filament or trichome is 5 microns in diameter.