The naked mole-rat (Heterocephalus glaber), also known as the sand puppy or desert mole rat, is a burrowing blesmol native to parts of East Africa and is the only species currently classified in the genus Heterocephalus. The naked mole-rat and the Damaraland mole-rat are the only known eusocial mammals. It has a highly unusual set of physical traits that enable it to thrive in an otherwise harsh underground environment; it is the only mammalian thermoconformer.
The mole rat lacks pain sensitivity in its skin, and has very low metabolic and respiratory rates. While traditionally considered to belong to the same family as other African mole-rats, the Bathyergidae, more recent investigation suggests that the naked mole-rat is sufficiently divergent to be placed in a new, separate family, Heterocephalidae. The mole rat is also remarkable for its longevity and its resistance to cancer.
Typical individuals are 8 to 10 cm (3 to 4 in) long and weigh 30 to 35 grams (1.1 to 1.2 oz). Queens are larger and may weigh well over 50 grams (1.8 oz), the largest reaching 80 grams (2.8 oz). 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. About a quarter of their musculature is used in the closing of their jaws while they dig – about the same proportion that is utilized in the human leg. They have little hair (hence the common name) and wrinkled pink or yellowish skin. They lack an insulating layer in the skin. source