The naked mole-rat is also called the sand puppy, and the reason is pretty apparent. The sand puppy is a burrowing rodent that is native to some parts of East Africa.
The animal is a close relative of the blesmols and is the only animal in the genus Heterocephalus that is of the Heterocephalidae family.
- Family: Heterocephalidae
- Class: Mammalia
- Order: Rodentia
- Scientific name: Heterocephalus glaber
- Phylum: Chordata
- Length: 13 cm (Adult)
Many people only know the naked mole-rat as an animal that lacks pain sensitivity in its skin, and also has very low respiratory and metabolic rates.
While this animal was formerly considered to belong to one family as the other African mole-rats, Bathyergidae, recent investigation has placed it in a separate family, known as Heterocephalidae. Other remarkable features of the naked mole-rat include its longevity, resistance to cancer, as well as its oxygen deprivation.
Typical naked mole-rat individuals are usually 8 to 10 cm (3 to 4 in) long, and they weigh between 30 to 35 grams (1.1 to 1.2 oz).
The naked mole-rat queens are usually larger and may weigh more than 50 grams (1.8 oz), with the most significant getting up to 80 grams (2.8 oz). These rodents are well-adapted to their lives underground.
The eyes of these rodents are quite small, and their visual acuity is also very poor. They have thin and short legs; however, they are exceedingly adept at moving underground, and they can also move backward at the same speeds as they can move forward.
These rodents have large, protruding teeth that they use for digging, and their lips are sealed right behind the teeth, thus preventing soil from getting into their mouths while they dig.
About a quarter of their entire musculature is used in keeping their jaws closed while they dig.
That is about the same proportion that is used in the human leg. They look like they are entirely hairless, but have little hair and wrinkled yellowish or pink skin.
These rats also lack an insulating layer in their skin.
In the world of the naked mole-rat, the reproducing females are the dominant females. This is usually achieved by fighting for the dominant position, founding new colonies, or simply taking over once another reproducing female dies.
The reproducing female naked mole-rat tends to have bodies that are longer than that of other non-reproducing females of the same skull width. The measurement of female naked mole-rats before and after they became reproductive shows significant increases in their body size.
It is strongly believed that this trait does not randomly occur, or happens due to pre-existing morphological differences. It is believed to occur due to the actual attainment of the position of a dominant female.
As with the reproductive females of these rats, the breeding males have also been found to be bigger in size than their non-reproducing brothers but not as much so as is visible in the case of the females.
The reproductive males also feature visible outlines of the testes via the skin of their abdomens. Also, unlike the female rats, there are often multiple reproducing males.
The naked mole-rat lives in a subterranean habitat that imposes constraints on the circadian rhythm of both the male and female. Living every day of their life in constant darkness, most of this rodent possesses a free-running activity pattern, and they remain active both day and night, only sleeping for short periods a few times in between.
Distribution and habitat of the naked mole-rat
The naked mole-rat is not so common as it is native to the drier parts of East Africa’s tropical grasslands, predominantly Kenya, southern Ethiopia, and Somalia.
Clusters reaching an average of 75 to 80 individuals reside together in complex systems of tunnels in the arid African deserts. The naked mole-rats can build tunnel systems that stretch to as much as three to five kilometers (2–3 mi) in cumulative length.
Roles of the naked mole-rats
The naked mole-rat happens to be the first mammal that was found to display eusociality. This eusocial structure is much alike to what is found in termites, ants, and some wasps and bees.
Only one female (the queen) and between one to three males will reproduce, while the other members of the colony will function as workers. The queen and all the breeding males are able to begin breeding at one year of age.
All workers are naturally sterile, with the smaller ones focusing on gathering food and staying in the nest. In contrast, the larger workers are typically more reactive whenever there is a case of attack.
For the non-reproducing females, they appear to be suppressed reproductively, which means that the ovaries do not mature fully, and also, do not have the same hormone levels as the reproducing females.
For the males, there is little or no difference in the levels of hormone concentration between the reproducing and non-reproducing male rats.
In studies where the main reproductive female was excluded or died, one out of the available non-reproducing females would immediately take over and quickly become sexually active.
The non-reproducing rats of the colony will handle cooperative care of the pups that are produced by the reproductive female.
This happens by the workers foraging for food, keeping the pups from straying, grooming, contributing to tunnel extensions, and also keeping them warm.
Diet of the naked mole-rat eating
Naked mole-rats are known to feed mainly on very large tubers (these tubers weigh as much as one thousand times their average body weight) that they stumble on deep underground via their daily mining operations.
A single large tuber can provide food for a colony for months or even years. This is because the naked mole-rats only eat the inside of the tubers, but leave the outside and allow the tuber to regenerate.
Naked mole-rats may sometimes eat their own feces as well. This is suspected to be part of their eusocial behavior and also a means of sharing hormones from the existing queen.
Naked mole rats are mostly underground, so they are primarily preyed upon by snakes. The major predators are the Kenyan sand boa and the Rufous beaked snake, as well as various raptors. These creatures are most exposed to threats when they construct mounds and eject soil to the surface.
Conservation status of the Naked mole-rats
Naked mole-rats are lucky enough not to be one of the world’s threatened animals. They are quite popular in the drier areas of East Africa, and their numbers are increasing fast.
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