In our last two articles on Naked Mole Rats, we learned whether they are rats or they are moles. We learned about their colonies and colony structure and size, their food habits, their free-moving incisors and also learned why they are called naked. What we didn’t learn is that they don’t feel pain and that they don’t get cancer and also learned that they are thermoconformers. We will learn about these things in this set of 20 surprising Naked Mole Rat facts. So, continue reading…
Surprising Naked Mole Rat Facts: 1-5 | Respiration, Metabolism
1. Naked Mole Rats are adapted to live underground. This means they usually live with limited oxygen availability.
2. They have very small lungs but the oxygen affinity of their blood is very high. So, whatever oxygen they take in is efficiently used. Their respiration rate is also very low.
3. A Naked Mole Rat can stay alive in an environment of just 5% oxygen for nearly 5 hours. They can stay alive in an environment where oxygen percentage is only 20% and carbon dioxide percentage is 80%.
4. In atmospheres with 0% oxygen, they can survive for 18 minutes. In such conditions, they will lose consciousness and their heartbeat will drop to 50 bpm (beats per minute) from 200 bpm. Breathing will stop but attempts of sporadic breathing will be there. No tissue damage happens during this period.
5. If the Naked Mole Rat goes through a phase of prolonged hunger, its metabolism will simply drop to 25% of the actual metabolism rate, allowing it to stay alive for longer periods without food.
Surprising Naked Mole Rat Facts: 6-10 | Thermoregulation, Pain Sensitivity
6. Naked Mole Rats are thermoconformer animals. They are world’s only mammal thermoconformers. This means that unlike other mammals who regulate their body temperature and keep it fixed at a specific temperature (known as homeostasis), these creatures do not do so.
7. They are thermoconformers, which means that as and when the surrounding temperature changes, their body temperature changes. This means that the Naked Mole Rats are poikilothermic.
8. Scientists have found that they can switch from being poikilothermic to homeothermic if the temperature reaches higher than 28°C. They will use behavioral thermoregulation when temperatures drop. For example, they will cuddle or bask in sun-warmed shallow areas of the tunnel and when they become hot, they will simply retreat to cooler areas of the tunnels at greater depths.
9. Coming to pain sensitivity, they don’t have something called Substance P. Substance P is a neurotransmitter that sends pain signals to CNS or central nervous system. When exposed to capsaicin or acid, they just don’t feel pain.
10. Scientists actually injected them with Substance P and found that they start experiencing pain but only to capsaicin but not to acids. This led the scientists to believe that since they live in carbon dioxide-rich environment, acid buildup in body is normal and hence, to prevent pain, they don’t have Substance P.
Surprising Naked Mole Rat Facts: 11-15 | No Cancer for Them
11. Yes, yes, Naked Mole Rats are cancer-resistant. They accomplish this via several means. First line of defense is the presence of gene p27. This gene prevents cell division once a certain number is reached by a group of cells.
Unfortunately, earlier this year, scientists found two captive Naked Mole Rats that had tumor. Once the tumors were removed, they lived cancer-free. Scientists want to find out what caused the tumor as they are usually not prone to cancer. Source.
12. In addition to p27 gene, they also have p16 gene in them. This p16 gene has pretty much the exact same function as p27 except that the threshold for the number of cells of p16 is lower compared to p27 gene.
13. Scientists also found out that they also produce high amounts of HMW-HA or extremely high-molecular-mass hyaluronan. It is a sugary substance – a lubricant that prevents cancer formation. In humans HMW-HA is 5 times less than that in Naked Mole Rats.
14. The same scientists who came up with the information on HMW-HA (the scientists are from University of Rochester) also found that the ribosomes that these creatures have produce proteins that are extremely error-free. Hence, no cancer.
15. Science – a journal – named the Naked Mole Rat as ‘Vertebrate of the Year’ for 2013 because of their HMW-HA and error-free proteins.
Surprising Naked Mole Rat Facts: 16-20 | Lifespan, Reproduction
16. The Naked Mole Rats have unusually high lifespan among rodents. They can live up to 32 years. Well, no one really knows why they live so long but a couple of theories have been put forward. They are:
- Their protein stability is responsible for their longevity (remember they have error-free proteins).
- They can reduce metabolism rate substantially when needed and hence, the oxidative stress causing age-induced damage is very low and hence, the longevity.
17. The Queen of a colony will mate only with a few males in the colony. They will stay in relation for several years. Only the Queen remains capable of reproducing while other females in the colony will usually remain temporarily sterile.
18. The Queen will usually select male Naked Mole Rats that are not her kins and are unfamiliar to her. She does this to prevent inbreeding. The other sterile females will mate but will not produce any babies. Those reproductively inactive females will not have any male preference. They will copulate with just any male.
19. The Queen will have a gestation period of 70 days. She will then give birth to a litter of pups ranging between 3 and 12 in number. However, the litter may be as large as 28 pups. In the wild, the Queen will breed only 1 time a year provided the litter survives. If the litter fails to survive, she can mate again within the same year.
20. The Queen mother will nurse the newborn litter for just 1 month. After that, other members of the colony will feed the litter with fecal pap until they reach the age where they can eat solid food.