Haematococcus pluvialis algae, flagellate form, microscopy
Light microscopy of the flagellated form of the alga Haematococcus pluvialis. This is a common alga in freshwater environments. Under normal conditions it photosynthesises using a large chloroplast and has two flagella that allow it to move around. When stressed it enters a dormant phase in which the cell produces a large amount of the red pigment astaxanthin, which protects it from ultraviolet radiation damage when its ponds dry up. This pigment is responsible for the pink staining of dried out birdbaths, and may be a cause of so-called 'blood rain'. Animals feeding on the algae accumulate the pigment, which is carried up the food chain and is responsible for the pink colour of shrimp and flamingoes. The pigment is widely used in foods and cosmetics. Filmed with differential interference contrast illumination. Magnification on the sensor: x400.