Dear colleagues, My co-authors and I are pleased to share our new publication in *Marine Mammal Science*, entitled: Nares modulation in breathing cetaceans reflects respiratory mechanics I am happy to share a copy of the publication with anyone interested! You can reach me at the following email address: ncnemeth@hawaii.edu Summary: Cetaceans possess highly specialized respiratory systems that facilitate efficient gas exchange during brief surfacing intervals. Recent observations have shown that baleen whale blowholes undergo shape changes during breathing and exhibit between-breath variation in size, yet no studies have quantified dynamic changes in blowhole area throughout the breath. Using publicly available drone footage across multiple mysticete and odontocete species, we quantified changes in nares area throughout the respiratory cycle and show that blowholes are dynamically modulated—remaining relatively constricted during exhalation and rapidly expanding during inhalation. Across species, nares area approximately doubled from the end of exhalation to the maximum area during inhalation, with the largest increase approaching a fivefold expansion. We propose that this modulation reflects fundamental respiratory mechanics, with narrowed nares during exhalation supporting lower airway patency, reducing ventilatory effort, and aiding water clearance, while widened nares during inhalation may stabilize the upper airways, reduce resistance, and facilitate high flow rates and tidal volume. The observed nares expansion curves during inhalation closely resemble inspiratory flow-rate curves measured during cetacean spirometry studies, suggesting that, with proper validation, nares expansion may provide a useful proxy for estimating tidal volume in free-ranging animals. Taken together, our findings suggest that cetacean blowholes are not merely passive conduits for airflow, but actively modulated structures that form an integral part of an extremely efficient respiratory system. Best, Cameron