Final answer:
Brown algae (Phaeophyceae) contain photosynthetic pigments such as chlorophyll a, chlorophyll c, ß-carotene, and fucoxanthin, with the latter giving them their characteristic brown color.
Step-by-step explanation:
In Phaeophyceae, commonly known as brown algae, the major photosynthetic pigments include chlorophyll a, chlorophyll c, ß-carotene, and fucoxanthin. Unlike the chlorophylls found in higher plants, chlorophylls in Phaeophyceae align more closely with the pigmentation seen in stramenopiles, a group that includes diatoms and golden algae.
The fucoxanthin pigment gives the brown algae their characteristic color, allowing them to absorb light more efficiently in deeper or dimmer waters. As a storage carbohydrate, brown algae use laminarin, which is different from the starch found in green algae and land plants.