Today I’ll be writing on a very interesting animal.
The Naked Mole Rat.
A weird looking but amazing creature whose lack of regard for existing natural laws has made it highly distinguishing. Even went as far as defying the gompertz law..
A member of the Order-Rodentia, family-Heterocephalidae, Genus-Heterocephalus, H.glaber specie, this hairless rodent (thus its name) is also known as sand puppy or desert mole rat.
There are other types of mole rats like the blind mole rats, African mole rats, Nigerian Mole rats, Indian mole rats, short tail mole rats, but we shall stick with the naked mole rat for the purpose of this post.
They all however, good burrowing skills living most of their life in harsh underground environment feeding majorly as an herbivore complimented with feeding on their own feaces.
TAXONOMY:
Clearly stating out;
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Heyerocephalidae
Genus: Heterocephalus
Specie: Heterocephalous Glaber.
Common name: Naked mole rat.
DESCRIPTION
This eusocial mammal( highest social classification) has some unusual set of physical traits that ensure its survival in harsh conditions.
Physically, the naked mole rat measures about 8-10cm long and weighs about 30-35 gms. They have small eyes and poor vision, thin and short legs that are specialized for rapid movements within their burrow. They can actually move backwards, as fast as they can move forward.
Their large protruding teeth serves as a tool for their digging. The lips are sealed behind the teeth. This is to keep sand from filling up their mouths while they are digging.
The naked mole rat is hairless and tubular, with a wrinkled body. It also has pinkish or yellowish skin lacking an insulating area. This making it look like a tiny walrus.
The Queens are larger and weighs over 80 grams.
WHERE CAN THEY BE FOUND?
The Naked Mole rat Can be found in Central Ethiopia, Somalia, Djibouti, much of northern and eastern Kenya. Also found as far as the border of tsavo west national park and voi town.
They live in the arid areas of these countries characterized by low rainfall and high temperature living in hard consolidated lateritic loams although they can also live in pure sand gypsum laterite.
These areas are most often with minimal development and agricultural activities.
The naked mole rat as weird as it may look has got a lot of specialized and morphological characteristics that defines the specie, makes them highly distinguished and above all ensure it’s survival.
Reproduction/Colony
The naked mole rat reproduces and lives in colonies led by one dominant rat I.e the queen. They exhibit eusociality as earlier mentioned. The colonies ranges in size from 20-30 mole rats with 25 on the average. Only the queen and three workers reproduces while their others function primarily as a worker.
Burrows are dug by the workers. This is done using thier prominent teeth and snout. Roots and bulbs are also gathered for feeding. The smaller workers focus on feeding and maintaining tunnels while the bigger workers are in charge of the security of the burrows. The workers could also be frequent workers, performing tasks as the name implies and infrequent workers performing their task at a much slower pace.
The non-reproducing members of the colony pertake in the cooperative care of pups produced by the reproducing females. This happens by keeping them from straying, keeping them warm, grooming and making them contribute to the extension of their tunnels.
Naked mole rats breed once a year in the wild and all year round in captivity with an average gestational age of 70 days. A typical litter comprises of 3-12 pups with an average of 11 pups per litter.
Respiration/Metabolism
This is a very big deal affecting this specie so so positively. With a very low respiratory and metabolic rate, thus minimally using available oxygen. This is an adaptation due to the limited oxygen found in its tunnel. The lungs are quite small with their blood possessing very strong affinity for oxygen intake.
Studies have shown that the naked mole rat can survive at least 5hours in an environment with only 5 percent oxygen without showing signs of distress..
It survived 18 minutes in a zero oxygen area but non recorded the test for 30 minutes.
A major reason for its ability to survive for a while without Oxygen was attributed to the reliance on fructose for Adenosine triphosphate[atp],(which is a form of energy utilized during breathing) as against glucose. In anerobic glycolysis using fructose, lactic acid is formed but does not inhibit the pathway thus atp mobilization is continuous as against mobilization of glucose for anerobic glycolysis. However, it is yet to be discovered how these animals manage to withstand tissue damage despite the incessant acidosis..
Thermoregulation
Temperature regulation in a naked mole rat is quite different to that seen in other mammals. They are thermoconformers rather than thermoregulators. Their body temperatures simply tracks and adjusts to that of its environment. There is however, some claims that the rat might have a distinct temperature rhythm not coupled to any environmental factor. There is a considerable relationship between the consumption of oxygen and the temperature switches from a typical poikilothermic pattern to a homoethermic mode when temperature is at 28 degree centigrade or more. They could also employ behavioral mode of thermoregulation in some circumstances especially in a cold environment.
For example, hot naked mole rats, retreat to deeper and cooler parts of their burrows. Conversely when they get cold, they huddle together and seek the shallow parts of the burrows warmed by the sun.
Longevity.
Naked mole rats are the longest living rodents with a reported life span of over 30 years. As mentioned earlier, they defy the dreadful law of death-”Gompertz law” which states that the risk of death for a typical mammal grows exponentially after they reach sexual maturity. Simply put, the probability of death in humans during a given year doubles every eight years. That means death comes faster as you get older.
But this doesn’t hold for the naked mole rat.
The reason for their longevity has been debated. It is being thought to be related to their ability to reduce their metabolism to the barest minimum when facing harsh conditions thus preventing tissue damages due to oxidative stress.
Their protein stability has also been suggested to be another possible cause of longevity. Because of this, efforts have been made to sequence the genetic make up of the Rat and harness it's amazing attributes.
Genes related to mitochondria and oxidation reduction processes were found in high levels when compared to a mice suggesting a possible contribution to their longevity.
Resistance to Cancer.
Cancer is essentially just a bunch of cells that divides out of control. Defense mechanisms known as senescence has evolved in humans and or their organism to keep them in check.Cellular senescence in which cells permanently stop dividing is one way of avoiding cancer. But it also indicates aging tendencies and tissue deterioration.
In humans, as in mice, aging and cancer have competing interests,says Vera Gorbunova, "In order to prevent cancer, you need to stop cells from dividing. However, to prevent aging, you want to keep cells dividing in order to replenish tissues.
Source
Studies in recent times have shown a promising anti aging therapy in the removal of senescent cells. That has inpired the development of a new class of drugs called senolytics designed to benefit humans.
A short fall to this finding is that Senescents can still metabolize leading to some of the damaging effects on age. But in a naked mole rat, the senescent cells are better organized and do not encounter such finding.
Insensitivity to Pain.
Another characteristic of the naked mole rat. It lacks “substance P” on it’s skin which is a key neurotransmitter sending pain signal to the central nervous system.
This has been proposed to be an adaptation to animal living in an environment with low oxygen tension and high concentration of carbon dioxide.
This kind of condition produces so much acid in the mammalian tissue which will elicit intense amount of pain if a neurotransmitter was in place.
Further more, the lack of “substance P” has also been related to a lack of histamine induced itching/scratching behavior of rodents.
Female mate choice.
The reproductively active female have got some specifications and this happens to be one of the very interesting facts about the female naked mole. They tend to always want the unfamiliar males for mating. Whereas the unreproductively active female do not really select their man. Anything could serve well for them.
This is an adaptation by the female rat to prevent inbreeding. Inbreeding is prevented because it may lead to the expression of deleterious alleles.
Diet.
The naked mole rat generally feeds on tubers which they find underground during burrowing activities.
A tuber could last a colony for years as they eat from inside allowing the tuber to regenerate from the outer part. They sometimes feed on their own faeces.This is a part of their eusocial behavior. Its also a means of sharing hormones from the queen.
The rats are primarily preyed upon by snakes including beaked snakes, boa, as well as raptors.
KEYNOTES
The naked mole rats according to its name lives naked. It lacks hair on it’s skin.
They have a gestation period of about 70 days breeding once in a year in the wild and all year round in captivity. A bred litter consist of an average of 11 pups.
They live in colonies with an average of 25 rats per colony. The queen is the head of the colony. The queen and three special workers breed while the rest are solely workers.
The naked mole rat can remarkably strive in an environment with very low oxygen concentration. Studies have even shown that it can live comfortably in an environment with zero concentration for 18 minutes. An adaptation implicated anatomically by the possession of a small lung and physiologically by having blood with high oxygen affinity.
Longest living rodents known to man with an average life span of 30 years defying the gompertzian law of mortality stated earlier in this post. Low basal metabolic rates in conjunction with some genetic peculiarities have been proposed has the leading cause of this longevity.
These rodents have some form of cancer resistance. Attributed to their well organized senescence activity, scientist are looking forward to exploit this quality for the good of mankind in creating better treatment options for cancerous ailments.
They are insensitive to pain because they lack the neurotransmitter signaling pain to the central nervous system.
They lack insulating fats in their skin and are poikilothermic, homoethermic, thermoconformers thermoregulators. They also exhibit behavioral thermal regulation. Huddling together when it’s cold, seeking cold deeper down their burrow when it’s so hot and vise versa when it’s a cold environment.
The reproductive female naked mole rats are quite selective in their mating choices.
They prefer unfamiliar (non-kin) males. This is an adaptation to prevent inbreeding which can have a genetic implication (expression of deleterious alleles).The naked mole rat is a highly specialized and adaptive mammal designed to ensure its survival in any condition it finds it self.
This is definitely the reason they are not threatened with a wide spread base in the drier regions of east Africa.
They also posses some qualities which if well studied, could be highly beneficial to humans especially in the areas of molecular biology and medicine.
Thank you for reading!
All Image Sources Are Stated In Text.
Text Sources:
http://www.go4thesummit.com/KiliAnimals.html
http://creatures-of-the-world.wikia.com/wiki/Naked_Molerat
https://newatlas.com/naked-mole-rat-longevity/53319/
http://www.rochester.edu/newscenter/naked-mole-rats-cancer-aging-longevity-295472/
https://haydensanimalfacts.com/2015/10/04/5-interesting-facts-about-naked-mole-rats/
https://doi.org/10.1007/s00216-015-8785-0
https://en.wikipedia.org/wiki/Naked_mole-rat
