Naked Mole-Rat

## Description

The Naked mole-rat (Heterocephalus glaber) is a burrowing rodent native to parts of East Africa. It is closely related to the blesmols. The Naked mole-rat exhibits a highly unusual set of physical and behavioral traits that allow it to thrive in a harsh underground environment. The Naked mole-rat lacks pain sensitivity in its skin and has very low metabolic and respiratory rates. It is also remarkable for its longevity and its resistance to cancer and oxygen deprivation.

## Appearance

The eyes of Naked mole-rats are quite small, and their visual acuity is poor. Their legs are thin and short; however, they are highly adept at moving underground and can move backward as fast as they can move forward. Their large, protruding teeth are used to dig and their lips are sealed just behind the teeth, preventing soil from filling their mouths while digging. Naked mole-rats have little hair (hence the common name) and wrinkled pink or yellowish skin. They lack an insulating layer in the skin.

## Distribution

Naked mole-rats are found in East Africa, predominantly in southern Ethiopia, Kenya, Somalia, and Djibouti. They inhabit drier parts of the tropical grasslands and savanna.

## Behavior

Naked mole-rats are eusocial mammals (the highest classification of sociality). They live in clusters averaging 75 to 80 individuals. Only one female (the queen) and 1 to 3 males reproduce, while the rest of the members of the colony function as workers. Smaller workers focus on gathering food and maintaining the nest, while larger workers are more reactive in case of attack. Non-reproducing members of the colony are involved in the cooperative care of the pups produced by the reproducing female. This occurs through the workers keeping the pups from straying, foraging for food, grooming, contributing to the extension of tunnels, and keeping them warm. Clusters live together underground in complex systems of burrows. These animals build tunnel systems that can stretch up to 3-5 kilometers (2-3 mi) in cumulative length. Tunnels have chambers, rooms with food, and toilet areas. Naked mole-rats find their food through their mining operations deep underground because they never come above ground. Living in constant darkness, most Naked mole-rats possess a free-running activity pattern and are active both day and night; they sleep for short periods of time several times in between.

## Diet

Naked mole-rats are herbivores. They feed primarily on very large tubers (weighing as much as a thousand times the body weight of a typical mole-rat). A single tuber can provide a colony with a long-term source of food - lasting for months, or even years, as they eat the inside but leave the outside, allowing the tuber to regenerate. Naked mole-rats sometimes also eat their own feces.

## Reproduction

Naked mole-rats have a polyandrous mating system in which one female mates with several males during one breeding season. In each cluster, there is only one queen and 1-3 breeding males. The relationships between the queen and the breeding males may last for many years; other females are temporarily sterile. Queens live from 13-18 years and are extremely hostile to other females behaving like queens or producing hormones for becoming queens. When the queen dies, another female takes her place, sometimes after a violent struggle with her competitors. In the wild, Naked mole-rats usually breed once a year, if the litter survives. In captivity, they breed all year long and can produce a litter every 80 days. The queen gives birth to a litter that typically ranges from 3 to 12 pups but may be as large as 28. The gestation period lasts about 70 days. The young are born blind and weigh about 2 grams (0.07 oz). The queen nurses them for the first month; after which the other members of the colony feed them feces until they are old enough to eat solid food. Both females and males become reproductively mature at one year of age.

## Population

### Population threats

There are no major threats to Naked mole-rats at present.

### Population number

According to IUCN, the Naked mole-rat is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.