Dear Marmamers We are sharing our new open access study just published in "Journal of Experimental Biology" where we successfully used electrical impedance tomography (EIT) to measure tidal volume in bottlenose dolphins and Cape fur seals, both on land and in seawater. EIT is a non-invasive imaging technique that tracks changes in air distribution in the lungs in real time. It's widely used in human medicine, but until now it hadn't been validated for marine mammals in water. One of the biggest hurdles has always been the conductive marine environment, but we show that it works. In both dolphins and fur seals, EIT closely tracked spirometry-derived tidal volume and produced dynamic regional images of ventilation. That means we can now see not just how much air moves, but where it moves within the lungs. The exciting part is what this makes possible. For decades, our understanding of lung compression, alveolar collapse, and gas redistribution during diving has relied heavily on models and indirect evidence. This study lays the groundwork for directly visualizing those mechanics in living animals. While we're currently limited to surface and static conditions, this is an important step toward imaging lung function during controlled dives. Underwater respiratory imaging in marine mammals is no longer just theoretical, it's starting to become technically achievable. We hope you find it interesting! Best, Andreas Title: Using electrical impedance tomography to estimate tidal volume in bottlenose dolphins and cape fur seals in seawater and on land Authors: Fahlman, A., Wells, R., West, N., Allen, A., Jabois, A., Gallagher, T., Larsson, J., Strom, E., Mosing, M., Harek, T., Adler, A. Journal: Journal of Experimental Biology, 229, jeb251412. doi:10.1242/jeb.251412 Link to the paper: https://journals.biologists.com/jeb/article/229/4/jeb251412/370865/Using-ele... Abstract: Marine mammals possess specialized respiratory adaptations that enable efficient gas exchange and resilience to extreme pressures during diving, yet direct observation of lung mechanics under pressure has been logistically challenging. Electrical impedance tomography (EIT)measures real-time changes in thoracic impedance, and provides continuous, regional maps of pulmonary air distribution. We validated EIT for estimating tidal volume (VT) in bottlenose dolphins (Tursiops spp.) and Cape fur seals (Arctocephalus pusillus) both on land and in water. EIT reliably tracked VT in both taxa, showing strong within-trial consistency, with between-trial variability attributable to belt placement, body position and electrode contact. EIT also generated dynamic functional images of regional ventilation, revealing spatial and temporal patterns of lung filling and emptying. These results demonstrate that EIT is the first non-invasive imaging method validated for marine mammals in seawater, representing a critical step toward visualizing lung function during diving.