Carotenoid is a group of yellow to brown pigments. The carotenoids are formed of yellow carotene and yellow to brown xanthophyll. They are protective pigments; which also transfer the light waves to chlorophyll. Both Carotenes and Xanthophyll are insoluble in water; but soluble in chloroform.
Carotenes: Mainly there are four types of carotenes present. They are carotene -a, -B, -e, -Y and lycopene. Most of the algae has B- Carotene which is replaced by carotene-a in the Siphonales, Cryptophyta and red algae. In the Charophyta the carotene -B is replaced by carotene -Y and lycopene. Both the carotene-B and carotene-e is present in Bacillariophyta.
Xanthophylls: The diatom contains the xanthophyll such as fucoxanthin and diatoxanthin. Pyrrophyta has the Peridinin pigment and myxoxanthin is present in cyanophyta. The characteristics of red algae are the presence of Taraxanthin and in Euglenophyta is the antheraxanthin. The fucoxanthin is the supplementary pigment in Bacillariophyta and Phaeophyta. The xanthophyll absorbs blue and green light.