Yesterday I promised you guys that I will bring to your attention a new strange animal each and everyday. Today I want to introduce you to what is by far the world's weirdest mammal. Think this is a bold claim? I am sure you will agree with me after reading the post. And I am sure some of you won't believe the things you are about to read, this is why I will make sure to properly reference every bit of information!
So, today's strange animal is the...
Naked Mole Rat
Scientifically described as Heterocephalus glaber, the naked mole rat is quite a scary looking critter, isn't it? Rest assured, with an average size of only 10 cm (4 inches) it's totally harmless. And being a burrowing rodent found only in East Africa, chances are you will never encounter one! If you really want to see one, your best bet is to visit a zoo or become a cancer researcher. Wait, what? Remember when I told you this is a truly strange mammal? The naked mole rat features a unique combination of physiological traits that make it so... unmammaly! Being almost immune to cancer is just one of them!
Now, let's learn more about these traits. If you are too lazy or busy for the details just scroll down for the TL;DR version:
1) Pain? What is That?
The skin of the naked mole-rats appears to be immune to pain! Research has shown that these animals are totally immune to certain types of pain that other animals find extremely painful. Specifically, researchers have discovered that naked mole rats "show a unique and remarkable lack of pain-related behaviors to two potent algogens, acid and capsaicin. Furthermore, when exposed to inflammatory insults or known mediators, naked mole-rats do not display thermal hyperalgesia." [1]
The reason for this is that the species lacks a key neurotransmitter called substance P. This neurotransmitter is responsible in mammals for sending pain signals to the central nervous system. Interestingly, when they are injected with the substance, the pain signaling begins to somewhat work, but only with capsaicin and not with acids. This pain resistance is believed to be an adaptation to the high levels of carbon dioxide found in their habitat, which causes acid to build up in their body.
2) Live Long And Prosper!
Most rodents have a life span of a couple of years, or less. The naked mole rat however is a different story, with a record-breaking, maximum lifespan of at least 31 years! Why the species lives so long is not yet known, but is believed to have ties to their extremely low metabolism. [2] And speaking of metabolism..
3) Oxygen & Food is overrated!
These critters live in deep burrows where oxygen and food is limited and as a result they have evolved accordingly. The species has very small lungs and their blood has a high efficiency for oxygen uptake. For their size. their respiration and metabolic rate is only 2/3 of what we would expect considering their rodent nature. And if things get tough, they can reduce their metabolic rate by a further 25 % in periods of famine!
To give you an example, research has shown that individuals can survive with no problem for at least 5 hours in air that contains only 5% oxygen, with no signs of distress or reducing activity levels. What about 0% oxygen? How much would you survive? 1,2 maybe 3 minutes? That's nothing! The naked mole rat can survive for 18 minutes without suffering any permanent damage! However, this seems to be the limit and none has survived a test of 30 minutes. [3]
4) Cancer? What is that?
You know the saying. Cancer sucks, unless you are a naked mole rat. Ok, I made that up :) Naked mole rats appear to be almost immune to cancer. Actually, cancer in an individual has never been observed in nature. There is only one report of two individuals ever getting cancer, but both were born and grown in a zoo, in an environment that had 21% atmospheric oxygen compared to their natural 2–9%, and scientists believe that this is what might have promoted cancerogenesis.
The mechanisms behind their apparent cancer immunity are not understood fully but there are some theories going on. According to one of by researchers at the University of Rochester, these rodents have ribosomes that produce "extremely error-free proteins." [4]
5) Thermoregulation?Pfffff! Too busy for that!
All mammals share a common trait. In all of us, the body temperature is fixed to a standard temperature range. Anything higher or lower is not normal and may lead to serious damage and even death. But every rule has an exception, and in this case the exception is the naked mole rat. They are thermoconformers rather than thermoregulators, and their body temperature is subject to changes, depending on the environment's temperature. As of today, they remain the only known mammalian thermoconformer. [5]
6) I am confused! I think I am an ant or something!
These unique creatures have one final trait I want to talk about. They are one out of the only two known mammalian species to exhibit eusociality, a social structure that is very similar to the one found in ants, termites, bees etc. The other one is the Damaraland Mole Rat (Fukomys damarensis).
Like ants, H. glaber forms colonies made of:
- Queen: Each colony has only one queen and the rest of the females are sterile. Her lifespan ranges from 13 to at least 18 years and she becomes extremely hostile to other females if they start showing queen-like behavior
- Breeding Males
- Workers: All workers are sterile. Like ants workers are further divided into castes. Some are tunnelers, some are "soldiers" protecting the nest and others food bringers.
Colonies range in size, anywhere from 20 to 300 individuals, with an average number of 75. [6]
TL;DR Version
Naked more rats are the world's most strange and unique mammal because:
- Scary, alien like looks
- They don't feel pain
- Remarkably long life span, longest living rodents by far
- They can survive with ease low oxygen levels that would kill most mammals in minutes
- Immune to cancer
- The only known mammalian thermoconformers
- They make ant-like colonies with a queen, workers and all!
Videos
Let me close today's post with two cool videos that show these beautiful & unique creatures in action:
References
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2214810/
- http://genomics.senescence.info/species/entry.php?species=Heterocephalus_glaber
- http://www.sunjournal.com/news/bplus/2017/04/23/naked-mole-rats-without-oxygen-live-plants/2115862
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3808608/
- https://www.datasci.com/solutions/thermoregulation/uncovering-the-secrets-of-the-naked-mole-rat
- http://science.sciencemag.org/content/212/4494/571
Images
All images used have been labelled for re-use on Google Images or are taken directly from the publication. If any image owner has an issue with this article, please contact me and I will address the issue.
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More Strange Animals To Come
If you enjoyed this post make sure to follow me and let's discover together some of the world's most strange and bizarre creatures. In the meantime, you may want to check the helicopter-like Bocydium globulare and the Red Lipped Batfish :)