International audienceLight harvesting and photochemistry is performed by photosystems coupled to specific antennae embedded in the thylakoid membrane, a common principle across diatoms, plants and green algae. Still, unique features of diatoms within this common principle have been unraveled in recent decades, likely resulting from the complex evolutionary history of diatoms. These unique features are found in (i) the lipid composition of the thylakoid membrane, ii) the spatial organization of the light harvesting complexes, and iii) their protein and pigment composition. This chapter summarizes current knowledge of these three specific features, with a focus on structural and functional properties