Small heat shock proteins (sHSPs) are found in all three domains of life (Bacteria, Archaea, and Eukarya) and play a critical role in protecting organisms from a range of environmental stresses. However, little is known about their physiological functions in red algae. Therefore, we characterized the sHSPs (PysHSPs) in the red macroalga Pyropia yezoensis, which inhabits the upper intertidal zone where it experiences fluctuating stressful environmental conditions on a daily and seasonal basis, and examined their expression profiles at different developmental stages and under varying environmental conditions. We identified five