Accessory pigments are light-absorbing compounds found in photosynthetic organisms. They are divided into three classes namely chlorophylls, carotenoids and phycobilins. Chlorophylls are subdivided into chlorophyll a, chlorophyll b(found in green algae) and chlorophyll c (in members of Chromista and dinoflagellates). Carotenoids are in red, orange and yellow in color and are further classified as xantophylls, which contains oxygen and carotenes. Phycoerythrobilin, phycourobilin, phycoviolobilin and phycocyanobilin are the four types of phycobilins. They are water-soluble and are in cytoplasm and stroma of the chloroplasts. Phycobilins are found in cyanobacteria and rhodophyta.
