Contrast red algae and brown algae.

The biological world has a diverse group of organisms, and different groups of organisms have different methods of nutrition.Among them, the organisms that can independently produce food by utilizing energy from sunlight are referred to as photosynthetic organisms.

Certain members of eukaryotes as well prokaryotes have the ability to photosynthesize.

The eukaryotic domain has four distinct kingdoms, and among them, all the members of the Kingdom Plantae and some members of the Kingdom Protist have the ability to photosynthesize.

Algae of the plant and protist kingdom are photosynthetic, and different algal group utilizes different wavelength of light in accordance with their photosynthetic pigment.

The primary pigment responsible for photosynthesis in the red algal group is phycoerythrin, and it also imparts red color to the algal body. In contrast, the pigment fucoxanthin is responsible for photosynthesis and body color in brown algae.

Red algae inhabit the deep layers of water bodies, while brown algae inhabit shallow layers or shore regions. The gametic cells in red algae are not flagellated, and fertilization depends on water currents. In contrast, the brown algal group produces flagellated gametes.