Not to mention Dolphins, seals and great whales?

yup, Sperm whales can hold their breath for 90 minutes they divert voluntarily all the blood to focus in the most important organs only.

for the humans, they hyperventilated to supersaturate their blood with oxygen. the mole rat was without such prep.

I was under the impression that hyperventilating is more about the reduction of CO2 in the lungs, rather than saturating the blood with oxygen.

It's basically to fool your body into thinking you've got enough oxygen (since it's C02 buildup in the lungs that triggers the out of air signal to the brain, not the lack of oxygen).

Hence why hyperventilating for, say, free diving can cause one to black out without triggering the suffocation reflex as one returns to the surface of the water.

Perhaps the article meant it was impressive for their body size.

Why is this more impressive at smaller scale?

Put simply, smallers organisms run hotter...have a higher metabolic rate. If you've ever felt the heartbrat of a cat, chicken, or hamster youll notice that it is significantly higher than your own, thus they require more oxygen relative to their size. Interestingly, the article points out that they become someone anaerobic metabolizing fructose, which doesnt require O2, throughout the body as a source of energy instead of glucose

Many people assume metabolism is proportional to surface area based on the argument above. This idea was first proposed by Max Rubner in 1883. In the 1930’s, Max Kleiber proposed that metabolism increases according to body mass raised to the power 3/4. If metabolism were proportional to volume, the exponent would be 1. If it were proportional to surface area, the exponent would be 2/3. But Kleiber’s law says it’s somewhere in between, namely 3/4.

Its not clear which, if either, theory is correct. But both agree t