Naked mole rats are cold blooded. It's a trait that they share with reptiles, but not with other mammals. The fact that they don't really regulate their own body temperature means they don't expend any energy staying warm, so they need less oxygen compared to more common rats and mice. And their hemoglobin, or red blood cells, are unusually sticky. They can pull oxygen out of air that would leave most mammals gasping for breath. Then, of course, there's the way naked mole rats live: in complex burrow systems with upwards of 200-300 inhabitants, where CO2 can easily accumulate.