If I tell you that a mammal has a social life of an insect, the cold-bloodedness of a reptile, and the metabolism of a plant, you would probably suggest me a psychiatrist. But let me tell you this is true. Bald and buck-toothed, naked mole rats may not fit into the pretty animals’ list, but they are extraordinary in many ways. They are 8 to 10 cm long and weigh 30 to 35 grams but with a lifespan of 30 years. Don’t judge them by their looks! They look kind of creepy and live under the ground of savannah lands in east Africa. Our special friend Mr Naked mole-rat is also known as ‘sand puppy’. As the name suggests, they are naked (almost no fur in the body) and blind burrowing rodents. They are so very unique and belong to a separate family of their own. This means that they not only have their own genus or species, but are also put into a separate family of Heterocephalidae, and let me tell you, this is rare in the field of taxonomy.
While studying their origin and phylogeny, it is observed that the naked mole-rat is a relative of the other African mole-rats, who share a common ancestor that lived 31 million years ago. The name Heterocephalus in Latin means a different head. The skull of the naked mole-rat has big buck teeth and a reduction in the number of molars and different digital formulae that distinguish it from all other mole rats. Their long streamlined body with short legs allows them to run forwards and backwards very quickly and their tusk-like teeth, used for digging, are on the outside of their lips so they can make tunnels without getting mud in their mouth. Whiskers on the face, body and tail allow the naked mole-rat to sense the underground environment by detecting objects and sensing vibrations. Considering many fossil records, biological characteristics, and genetic analysis of naked mole-rat, compared to other African mole-rats, they are in a class by themselves in terms of all ecological, morphological, physiological characteristics. They are just a group in themselves, which is why it makes sense to elevate them to a family status rather than have them be simply a genus within the family of African mole rats.
They have so many features we can talk about and discuss, but I chose to stick to 3 for the time being –
Eusociality, their ability to survive at low O2 level, and their special healing properties (anti-ageing, anti-cancerous).
- Naked mole rats are social mammals (eusocial), i.e., they live in colonies that more closely resemble insect hives, e.g., bees or ants. Each colony may have 300 individuals in them. Every colony has one queen, and the queen is the one who tells everybody else what to do and the only one to reproduce. And everyone else, regardless of sex, is a soldier or worker. This type of social structure is something we expect to see in certain insects, not mammals. Choosing someone as a leader or queen involves females showing their dominance over other females and can sometimes lead to a bloodbath, known as ‘mole-rat war’. The queen mates with four or five males and gives birth to an entire colony that can number up to a few hundred individuals. A queen can give birth to 20-25 pups at a time and can have as many as five litters in a year. All others serve specific working roles within the organization and do everything from expanding their tunnel systems in search of food to defending the colony from snakes and other invaders. Of course, we must not forget that they also help with the constantly regenerating litter of pups.
- Naked mole rats also have the unique ability to withstand extreme oxygen deprivation, also known as hypoxia. The presence of so many individuals in a closed burrow system depletes the air of most of its oxygen and reports claim that they can live without oxygen for up to 18 mins. This sabre-tooth, the sausage-shaped creature spends its entire life in underground burrows with up to 300 mates in the arid regions of East Africa conditions. These subterranean burrows are quite extreme, with incredibly low oxygen levels while carbon dioxide is high. Naked mole rats can thrive in low oxygen partly because they have abandoned one of the bodily functions that require the most oxygen, thermoregulation. The only mammalian thermoconformer
(body temperature changes according to the external temperature) species are considered cold-blooded (ectothermic). They also have a special type of haemoglobin, which has much more efficiency for using oxygen than ours. They stop moving, slow their breathing, and dramatically lower their heart rate, which conserves energy, and reduces oxygen demand. At the same time, they begin to metabolize fructose, just like plants (whereas we use glucose). Fructose is a sugar that can be used to make energy without burning oxygen.
- Their peculiar traits like cancer-immune and anti-ageing properties have evolved over millions of years to make them uniquely suited to survive in harsh conditions. Their size is similar to a mouse, which has a lifespan of about two years. However, mole rats can live for up to 30 years (that’s 450 in human years!). But even so, they show no sign of ageing. The mystery behind this eternal youth lies in another amazing trait: they are cancer-resistant. The secret of this incredible ability lies in the very thing that makes them look so weird. They pose a stretchy skin that is very loose and a good adaptation for living underground in tight tunnels with many other individuals. This stretchy skin is a result of a gloopy substance that only naked mole-rats appear to produce; it is known as Hyaluronan, and it is this substance that is known to give them their cancer resistance. Scientists are delving deep into this gloopy substance, trying to copy its extraordinary anti-cancer powers, which someday can be used by us to develop drugs to treat cancer. Naked mole-rats also have a unique cell proliferation response to cell density. They show a high cell death rate in certain conditions and produce tumour suppressors like P16and interferon-beta. It seems like naked mole rats are closer to humans than mice.
Thus we see how the naked mole-rat has achieved great success in its longevity, immunity, adaptation, and many other aspects of life in the desert. Therefore, although it may not be the dashing debonaire to grace a beauty pageant, the naked mole-rat, with its cool adaptations is one of the superheroes of the natural world and deserves our appreciation and respect. In near future, we might use them as model organism to study and find a cure for different cancers, or maybe we can stop ageing and enjoy our entire life the way we do in our 20s.
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Aryesh is currently pursuing his bachelor’s degree in Zoology at Ramakrishna Mission Vidyamandira, West Bengal. Cancer biology is his area of interest and in the future, he would like to research more about it. Along with studies he likes playing football, cooking and travelling. He may not be a professional writer, but his passion for science brings out the best in him.
He has completed his Masters in Medical Biotechnology from The Maharaja Sayajirao University of Baroda and is currently an active researcher in Molecular Epidemiology at The Centre for Cancer Epidemiology, Navi Mumbai. His journey in Science and Creativity began together during his childhood days. He believes that Art and Science indeed have a beautiful world altogether in them and sailing across its spectrum inspires him to sow his thoughts deep into Science and carve out the pillars of Art through them! Being a Science enthusiast and an Artist, he wishes to devote a good share of his life to wildlife and marine conservation as he feels that the creativity of nature needs to be taken care of in the current era.