While we are on the topic of whales, I found additional research published in the Proceedings of the National Academy of Sciences USA on these animals and how their hearts function that I find fascinating. Talk about extreme physiology!
Researchers from Stanford University were able to attach surface electrodes to blue whales using suction cups. This allowed them to measure – for the first time – how heart rate changes during foraging dives as well as when the animals surface in the open ocean. What they found is that heart rate slows to an average of only 4-8 beats per minute (bradycardia – lower than normal) during deep foraging dives and increases to 25-37 beats per minute (tachycardia – above normal) when the animals surface for air after diving. The slow heart rate during lunge diving is remarkable given the high energetic costs of diving that we discussed yesterday. Having a slow heart rate during dives is thought to allow the animals to conserve oxygen.
JA Goldbogen, DE Cade, J Calambokidis, MF Czapanskiy, J Fahlbusch, AS Friedlaender, WT Gough, SR Kahane-Rapport, MS Savoca, KV Ponganis, PJ Ponganis. Extreme bradycardia and tachycardia in the world’s largest animal. Proceedings of the National Academy of Sciences USA. 116(50): 25329-25332, 2019. 10.1073/pnas.1914273116