The naked mole-rat, also known as the sand puppy, is a burrowing rodent native to parts of East Africa. It has a highly unusual set of physical traits that allow it to thrive in a harsh underground environment and is the only mammalian thermoconformer, almost entirely ectothermic (cold-blooded) in how it regulates body temperature.

The naked mole-rat lacks pain sensitivity in its skin, and has very low metabolic and respiratory rates. The naked mole-rat is also remarkable for its longevity and its resistance to cancer and oxygen deprivation.

They are well adapted to their underground existence. Their eyes are quite small, and their visual acuity is poor. Their legs are thin and short; however, they are highly adept at moving underground and can move backward as fast as they can move forward. Their large, protruding teeth are used to dig and their lips are sealed just behind the teeth, preventing soil from filling their mouths while digging.

The naked mole-rat is well adapted to the limited availability of oxygen within the tunnels of its typical habitat. It has underdeveloped lungs and its hemoglobin has a high affinity for oxygen, increasing the efficiency of oxygen uptake. The naked mole-rat survives for at least 5 hours in air that contains only 5% oxygen; it does not show any significant signs of distress and continues normal activity. It can live in an atmosphere of 80% CO

2 and 20% oxygen.

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