A paper published in the journal Science offers an explanation into how marine mammals manage to store oxygen during long deep dives. The study extracted myoglobin, an iron and oxygen-binding protein, from terrestrial and marine mammals and compared the properties of each. Scientists have understood that high levels of the protein allow more oxygen to be stored, but until now, have not understood how this does not pack together and inhibit muscle function generally.

The new study shows that deep diving mammals have myoglobin that is positively charged and repels other similar molecules, allowing for higher concentrations of it in the muscles. This discovery has helped explain the “changes that took place in mammals’ bodies as they evolved from land-based animals to the aquatic, air-breathing creatures that inhabit the oceans today”.