Any of the granules, approximately 32 nm x 48 nm and consisting of highly aggregated phycobiliproteins, that are attached in arrays to the external face of a thylakoid membrane in algae of the phyla Cyanophyta and Rhodophyta, where they function as light-harvesting devices in photosynthesis. Excitation energy in the phycobilisome flows in the sequence: phycoerythrin, phycocyanin, allophycocyanin before passing to the antenna chlorophyll of photosystem II.
phycobilisome