Weird Naked Mole Rat Facts (Heterocephalus glaber)

Could These Curious Creatures Unlock the Secret of Immortality?

The naked mole rat, Heterocephalus glaber, lives in the drier regions of East Africa.
The naked mole rat, Heterocephalus glaber, lives in the drier regions of East Africa. Mint Images - Frans Lanting / Getty Images

Every species of animal has its unique traits. However, some of the characteristics of the naked mole rat (Heterocephalus glaber) are quirky bordering on downright weird. Some people think the rat's unique physiology could be studied to unlock immortality or find a way to prevent cancer. Whether or not this is true remains to be seen, but one thing is certain. The mole rat is an unusual creature.

Meet the Naked Mole Rat

The naked mole rat queen is larger than the other rats within a colony.
The naked mole rat queen is larger than the other rats within a colony. Geoff Brightling / Getty Images

It's easy to recognize the naked mole rat by its buck-teeth and wrinkled skin. The rat's body is adapted for life underground. Its protruding teeth are used for digging and its lips seal behind its teeth, to prevent the animal from eating dirt while burrowing. While the rat isn't blind, its eyes are small, with poor visual acuity. The naked mole rat's legs are short and thin, but the rat can move forward and backward with equal ease. The rats aren't completely bald, but they have little hair and lack an insulating fat layer beneath the skin.

The average rat is 8 to 10 cm (3 to 4 in) in length and weighs 30 to 35 g (1.1 to 1.2 oz). Females are larger and heavier than males. The rats are native to the dry grasslands of East Africa, where they live in colonies of 20 to 300 individuals. Naked mole rats are numerous within their range and are not considered to be endangered.

The rodents are herbivores, feeding primarily on large tubers. One large tuber can sustain a colony for months or years. The rats eat the interior of the tuber, but leave enough for the plant to regenerate. Naked mole rats sometimes eat their own feces, although this may be a social behavior rather than a source of nutrition. Naked mole rats are preyed upon by snakes and raptors.

The Only Cold-Blooded Mammal

A naked mole rat would feel cool to the touch.
A naked mole rat would feel cool to the touch. Karen Tweedy-Holmes / Getty Images

Human, cats, dogs, and even egg-laying platypuses are warm-blooded. As a rule, mammals are thermoregulators, able to maintain body temperature despite external conditions. The naked mole rat is the one exception to the rule. Naked mole rats are cold-blooded or thermoconformers. When a naked mole rat is too hot, it moves to a deeper, cooler part of its burrow. When it's too cold, the rat either moves to a sun-warmed location or huddles with its pals.

It Can Survive Without Air for a Time

Humans can't live very long without air.
Humans can't live very long without air. Dimitri Otis / Getty Images

Human brain cells start to die within 60 seconds without oxygen. Permanent brain damage typically sets in after three minutes. In contrast, naked mole rats can survive 18 minutes in an oxygen-free environment without suffering any harm. When deprived of oxygen, the rat's metabolism slows and it uses anaerobic glycolysis of fructose to make lactic acid to supply its cells with energy.

Naked mole rats can live in an atmosphere of 80 percent carbon dioxide and 20 percent oxygen. Humans would die from carbon dioxide poisoning under these conditions.

It's Highly Social

Naked mole rats and other mole rats form colonies, much like bees and ants.
Naked mole rats and other mole rats form colonies, much like bees and ants. Kerstin Klaassen / Getty Images

What do bees, ants, and mole rats have in common? All are eusocial animals. This means they live in colonies that have overlapping generations, division of labor, and cooperative brood care.

As in insect colonies, naked mole rats have a caste system. A colony has one female (queen) and one to three males, while the rest of the rats are sterile workers. The queen and males begin breeding at one year of age. The hormones and ovaries of worker females are suppressed, so if the queen dies, one of them can take over for her.

The queen and the males maintain a relationship for several years. Naked mole rat gestation is 70 days, producing a litter ranging from 3 to 29 pups. In the wild, naked mole rats breed once a year, providing the litter survives. In captivity, the rats produce a litter every 80 days.

The queen nurses the pups for a month. After this, smaller workers feed the pups fecal pap until they are able to eat solid food. Larger workers help to maintain the nest, but also protect the colony from attacks.

It Doesn't Die of Old Age

Biologically, an old naked mole rat and a young one are virtually indistinguishable.
Biologically, an old naked mole rat and a young one are virtually indistinguishable. R. Andrew Odum / Getty Images

While mice may live up to 3 years, naked mole rats can live up to 32 years. The queen doesn't experience menopause, but remains fertile throughout her lifespan. While naked mole rat longevity is exceptional for a rodent, it's unlikely the species holds the Fountain of Youth in its genetic code. Both naked mole rats and humans have DNA repair pathways not present in mice. Another reason mole rats may outlive mice is because of their lower metabolic rate.

Naked mole rats are not immortal. They die from predation and illness. However, mole rat aging does not adhere to the Gompertz law describing aging in mammals. Research into naked mole rat longevity may help scientists unravel the mystery of the aging process.

This Rat Is Cancer-Resistant

Unlike the naked mole rat, naked mice and other rodents are susceptible to tumors.
Unlike the naked mole rat, naked mice and other rodents are susceptible to tumors. littlepeggy / Getty Images

While naked mole rats can catch diseases and die, they are highly resistant (not entirely immune) to tumors. Scientists have proposed multiple mechanisms for the rat's remarkable cancer resistance. The naked mole rat expresses the p16 gene that prevents cells from dividing once they come in contact with other cells, the rats contain "extremely high-molecular-mass hyaluronan" (HMW-HA) which may protect them, and their cells have ribosomes capable of making nearly error-free proteins. The only malignancies discovered in naked mole rats were in captive-born individuals, which lived in a much more oxygenated environment than rats in the wild.

It Doesn't Feel Pain

Unlike the naked mole rat, furry rodents itch and feel pain.
Unlike the naked mole rat, furry rodents itch and feel pain. photography by Elsa Sendra / Getty Images

Naked mole rats neither itch nor feel pain. Their skin lacks a neurotransmitter called "substance P" that is needed to send pain signals to the brain. Scientists believe this might be an adaptation to living in poorly ventilated species, where high levels of carbon dioxide cause acid to build up in tissues. Further, the rats don't feel temperature-related discomfort. The lack of sensitivity may be in response to the naked mole rat's extreme habitat. 

Naked Mole Rat Fast Facts

Common Name: Naked Mole Rat, Sand Puppy, Desert Mole Rat

Scientific NameHeterocephalus glaber

Classification: Mammal

Size: 8 to 10 cm (3 to 4 in), weighing 30 to 35 g (1.1 to 1.2 oz)

Habitat: Dry grasslands of East Africa

Conservation Status: Least Concern (not endangered)

References

  • Daly, T. Joseph M.; Williams, Laura A.; Buffenstein, Rochelle (April 1997). "Catecholaminergic innervation of interscapular brown adipose tissue in the naked mole-rat (Heterocephalus glaber)". Journal of Anatomy. 190 (3): 321–326.
  • Maree, S. & Faulkes, C. (2008). "Heterocephalus glaber". IUCN Red List of Threatened Species. Version 2008. International Union for Conservation of Nature.
  • O'Riain, M. Justin; Faulkes, Chris G. (2008). "African mole rats: eusociality, relatedness and ecological constraints". In Korb, Judith; Heinze, Jörgen. Ecology of Social Evolution. Springer. pp. 207–223.
  • Park, Thomas J.; Lu, Ying; Jüttner, René; St. J. Smith, Ewan; Hu, Jing; Brand, Antje; Wetzel, Christiane; Milenkovic, Nevena; Erdmann, Bettina; Heppenstall, Paul A.; Laurito, Charles E.; Wilson, Steven P.; Lewin, Gary R. (2008). "Selective Inflammatory Pain Insensitivity in the African Naked Mole-Rat (Heterocephalus glaber)". PLoS Biology. 6 (1): e13. 
  • Thomas J. Park; et al. (Apr 21, 2017). "Fructose-driven glycolysis supports anoxia resistance in the naked mole-rat". Science. 356 (6335): 307–311.