The naked mole-rat (Heterocephalus glaber), also known as the sand puppy, is a burrowing rodent native to parts of East Africa. The naked mole-rat and the Damaraland mole-rat are the only known eusocial mammals, the highest classification of sociality. It has a highly unusual set of physical traits that allow it to thrive in a harsh underground environment and is the only mammalian thermoconformer, almost entirely ectothermic (cold-blooded) in how it regulates body temperature. The naked mole-rat lacks pain sensitivity in its skin, and has very low metabolic and respiratory rates. The naked mole-rat is also remarkable for its longevity and its resistance to cancer and oxygen deprivation.
Some characteristic of the naked mole-rat. Some details :
- The naked mole-rat is well adapted to the limited availability of oxygen within the tunnels of its typical habitat. The naked mole-rat survives for at least 5 hours in air that contains only 5% oxygen; it does not show any significant signs of distress and continues normal activity. It can live in an atmosphere of 80% CO2 and 20% oxygen. In zero-oxygen atmosphere, it can survive 18 minutes apparently without suffering any harm (but none survived a test of 30 minutes).
- The naked mole-rat does not regulate its body temperature in typical mammalian fashion. They are thermoconformers rather than thermoregulators in that, unlike other mammals, body temperature tracks ambient temperatures.
- The skin of naked mole-rats lacks neurotransmitters in their cutaneous sensory fibers. As a result, the naked mole-rats feel no pain when they are exposed to acid or capsaicin.
- Naked mole-rats have a high resistance to tumours, although it is likely that they are not entirely immune to related disorders. A potential mechanism that averts cancer is an "over-crowding" gene, p16, which prevents cell division once individual cells come into contact (known as "contact inhibition"). The cells of most mammals, including naked mole-rats, undergo contact inhibition via the gene p27 which prevents cellular reproduction at a much higher cell density than p16 does. The combination of p16 and p27 in naked mole-rat cells is a double barrier to uncontrolled cell proliferation, one of the hallmarks of cancer.
-The naked mole-rat is also of interest because it is extraordinarily long-lived for a rodent of its size (up to 32 years) and holds the record for the longest living rodent. The mortality rate of the species does not increase with age, and thus does not conform to that of most mammals (as frequently defined by the Gompertz-Makeham law of mortality). Naked mole-rats are highly resistant to cancer and maintain healthy vascular function longer in their lifespan than shorter-living rats.
- The naked mole-rat is the first mammal discovered to exhibit eusociality. This eusocial structure is similar to that found in ants, termites, and some bees and wasps. Only one female (the queen) and one to three males reproduce, while the rest of the members of the colony function as workers. The queen and breeding males are able to breed at one year of age. Workers are sterile, with the smaller focusing on gathering food and maintaining the nest, while larger workers are more reactive in case of attack.
Source : Wikipedia