Photo: Rochelle Buffenstein / City College of New York
Quick: what is the toughest animal on earth? I mean the one that can withstand the most pain inflicted by burning acid without flinching. Did you think of a gorilla? A lion maybe? Or perhaps a charging bull?
Well, you'd be wrong: it is the naked mole rat. Here's why:
"They're the nicest, sweetest animals I've ever worked with — they look frightening, but they're very gentle," said neurobiologist Thomas Park at the University of Illinois at Chicago. [...]
As vulnerable as naked mole rats seem, researchers now find the hairless, bucktoothed rodents are invulnerable to the pain of acid and
the sting of chili peppers.
Why are they so impervious to acid?
Scientists theorize naked mole rats evolved this insensitivity to acid due to underground living. The rodents exhale high levels of carbon dioxide, and in such tight, poorly ventilated spaces it builds up in tissues, making them more acidic. In response, the mole rats became desensitized to acid.
"To give you an idea of what they experience, we normally all breathe in carbon dioxide levels of less than 0.1 percent. If people are exposed to an air mixture with as low as 5 percent carbon dioxide, we'll feel a sharp, burning, stinging sensation in our eyes and nose," Park said. "We hypothesize that naked mole rats live in up to 10 percent carbon dioxide."