Flamingos feed on blue-green algae, diatoms and crustaceans. The primary food source for the lesser flamingos is the microscopic blue-green algae, Spirulina platensis, found in the warm alkaline waters of the Rift Valley Lakes. The characteristic pink or crimson colour of flamingos is caused by a pigment derived from carotenes, in particular canthaxanthin, found in the algae.