Physiology
The naked mole rat is well adapted for the limited availability of oxygen within the tunnels that are its habitat: its lungs are very small and its blood has a very strong affinity for oxygen, increasing the efficiency of oxygen uptake. It has a very low respiration and metabolic rate for an animal of its size, about 2/3 that of a mouse of the same size, thus uses oxygen minimally. In long periods of hunger, such as a drought, its metabolic rate can be reduced by up to 25 percent.
The naked mole rat does not regulate its body temperature in typical mammalian fashion, homeostasis. They are thermoconformers rather than thermoregulators in that, unlike other mammals, body temperature tracks ambient temperatures. The relationship between oxygen consumption and ambient temperature, however, switches from a typical poikilothermic pattern to a homeothermic mode at 28 °C. At lower temperatures, they use behavioural thermoregulation, as when cold, naked mole rats huddle together or bask in the shallow, more sun-warmed parts of their burrow systems. Conversely, when they get too hot, they retreat to the deeper, cooler parts of their tunnel system.
The skin of naked mole rats lacks a key neurotransmitter called substance P that is responsible in mammals for sending pain signals to the central nervous system. The naked mole rats feel no pain when they are exposed to acid or capsaicin. When they are injected with substance P, however, the pain signaling works as it does in other mammals, but only with capsaicin and not with the acids. This is proposed to be an adaptation to the animal living in high levels of carbon dioxide due to poorly ventilated living spaces, which would cause acid to build up in their body tissues.
Naked mole rats' substance P deficiency has also been tied to their lack of the histamine-induced itching and scratching behavior typical of rodents.
Read more about this topic: Naked Mole Rat
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