Flamingos filter-feed on brine shrimp and blue-green algae. Their beaks are specially adapted to separate mud and silt from the food they eat, and are uniquely used upside-down. The filtering of food items is assisted by hairy structures called lamellae which line the mandibles, and the large rough-surfaced tongue. The pink or reddish color of flamingos comes from carotenoids in their diet of animal and plant plankton. These carotenoids are broken down into pigments by liver enzymes.[18] The source of this varies by species, and affects the saturation of color. Flamingos whose sole diet is blue-green algae are darker in color compared to those who get it second hand (e.g. from animals that have digested blue-green algae).[19]