Number 2
Naked mole rat
The naked mole rat (Heterocephalus glaber) also known as the sand puppy or desert mole rat, is a burrowing rodent native to parts of East Africa and is the only species currently classified in the genusHeterocephalus. 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, has a lack of pain sensation in its skin, and has very low metabolic and respiratory rates.