Diving physiology: lung capacity, heart, myoglobin

How cetaceans defy the physics of diving

The sperm whale dives to 2,250 m, Cuvier’s beaked whale to 2,992 m. These feats rest on an extremely specialised physiology: compressible lungs, a heart rate that falls from 25-37 bpm at the surface to 4-10 bpm during a dive (bradycardia), a myoglobin concentration 10 to 30 times higher than a human’s, and a respiratory exchange of 80-90% with each blow. This comparison tool sets out the key figures for 15 species.

Going further

Diving physiology is rounded out by the diving records, the swimming performance, the breath-hold calculator and the sensory adaptations.

Blood, heart, myoglobin: the secrets of extreme breath-holding

The deep divers, sperm whale, Cuvier’s beaked whale and pilot whale, accumulate spectacular adaptations. Their muscle myoglobin is exceptionally concentrated: ~67 mg/g in the sperm whale, ~60 mg/g in Cuvier’s beaked whale (Mirceta et al. 2013, Science), against ~5 mg/g in humans, a muscular oxygen store ten times larger.

Dive bradycardia lowers their heart rate to 4-8 beats per minute, which Goldbogen et al. measured directly in the blue whale in 2019. The rete mirabile (wonderful net), a dense vascular mesh, allows the selective vasoconstriction that reserves oxygen for the vital organs. Cuvier’s beaked whale holds the outright record: 2,992 m depth and more than 3 h 42 min of breath-hold (Schorr et al. 2014, PLoS ONE).