Carotenoids are accessory pigments that are responsible for predominantly yellow and orange coloration. Their color is usually masked by the presence of chlorophyll. They are present in all photosynthetic cells. If chlorophyll disintegrates for any number of reasons, these pigments may be oxidized to a red state. Most commonly seen in trees turning color in the fall, this oxidation has other implications in the marine environment to be covered in future articles.
Carotenes have secondary functions as antioxidants.
Xanthophylls consist of oxygenated carotenes such as neoxanthin, violaxanthin and lutein, all which have provide characteristic coloration through absorption, either functionally or incidentally. Fucoxanthin is a yellow pigment with primary absorption around 530 nm. Phicobilins are pigments first discovered in red marine algae. Primary types include the phycoerthrins, red pigments that improve and widen the absorption of chlorophyll in the middle of the spectrum. Blue pigments, called phycocyanins absorb at about 630 nm and narrow the absorption gap in chlorophyll-a in its respective spectral area.