Bangia atropurpurea (Mertens ex Roth) C. Agardh is a freshwater red alga species that is distributed worldwide. B. atropurpurea is highly adaptable due to its stress‐tolerance, which ensures survival under desiccation periods and under radiation extremes typical of the supra‐ and upper eulittoral zones. Whereas a number of previous investigations addressed some of the physiological and biochemical traits involved in stress‐tolerance, we studied the spatial arrangement of the mature (multiseriate) and immature (uniseriate) filaments and of selected bioorganic compounds along a gradient defined by distance from the waterline. Substantial physiological and biochemical differences were previously observed among phenological stages in the marine environment. In this study, we showed a nonrandom spatial structure of both phenological stages and photosynthetic pigments and photoprotective compounds, R‐phycocyanin and R‐phycoerythrin along the supralittoral‐eulittoral gradient. This observed pattern strongly suggests a complex interplay between physio‐morphological regulation and spatial arrangement of mature and immature filaments in conferring the typical stress tolerance of B. atropurpurea.