Stanford researchers report first recording of a blue whale's heart rate (2019)

This 2019 Stanford study made history with the first-ever recording of a blue whale's heart rate, a feat requiring a custom-designed tag with electrodes and accelerometers. The data revealed extreme physiological limits: the heart rate dropped to 2 beats per minute during deep dives and peaked at 37 beats per minute at the surface. It is a rare glimpse into a 200-ton creature's cardiovascular system, offering a data point unmatched in marine biology.