Monday, June 6, 2011

Naked Mole Rats

They say to not judge a book by its cover, but they might need a more convincing adage to keep us from judging the naked mole rat. Though a little hard to look at, these rodents have a lot more going for them than their horror movie-worthy appearance.

Naked mole rats are native to East Africa, living in elaborate underground burrows and tunnels that they dig with their large teeth (their lips are behind these teeth to prevent dirt from getting in their mouths). Their small bodies – 3 to 4 inches long and 30-35 grams – and short legs are ideal for navigating cramped tunnels; they can scurry quickly both backward and forward.

Mole rats rarely leave their burrows: their mostly hairless, almost pigment-less bodies don’t fair well in the sun and their weak, beady eyes give them poor visual acuity. Fittingly, mole rats live mainly on tubers – starch-rich vegetables that grow underground. Additionally, mole rats have naturally low metabolisms and eat relatively infrequently; they can reduce their metabolisms even further when food is scarce.

Unlike most mammals, naked mole rats can’t maintain homeostasis, or a consistent internal body temperature. When cold, mole rats huddle together or head to higher, more sun-warmed areas of their burrows. Likewise, they linger in deeper, colder tunnels to keep cool. Some might consider the mole rat “cold-blooded,” although the terms “cold-” and “warm-blooded” have fallen out with the scientific community, as they oversimplify the wide range of temperature regulation techniques.

Despite their odd physiology, it’s their social structure that’s really strange. Naked mole rats are one of only two eusocial species of mammals (the other being the less naked, Damaraland mole rat). Eusocial creatures, such as ants and bees, have one queen that does all the breeding for a group, while other individuals focus on protecting and feeding the colony. Indeed a mole rat queen breeds with one to three specially picked males to produce several litters a year, with up to 37 pups per litter (the largest litter of any mammal). The queen nurses newborns, while higher-ranking worker mole rats feed older pups tubers and – brace yourself – their own poop.

Mole rats might already seem the oddest mammals out there, but there’s more. Normally, the high level of carbon dioxide in the mole rats’ poorly ventilated tunnels would cause a build up of pain inducing acids in their bodies. However, mole rats lack the neurotransmitter that translates these acids into aching: in short, they don’t feel pain.

I’ll close with one last fascinating feature: because they have an extra gene that regulates cell growth, mole rats have been deemed “cancer proof.” Strange though they might be, some researchers have looked past the mole rat’s terrifying face and seen new hope for human cancer research. Although they might not end up the furry heroes of a Disney film, these hairless oddities may end up saving a lot of lives. I guess appearances aren’t everything after all.

Source: 123