Naked Mole Rat

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Naked Mole Rat Fossil range: Early Pliocene - Recent
Conservation status
Least concern (LC)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Rodentia Family: Bathyergidae Subfamily: Heterocephalinae Landry, 1957 Genus: Heterocephalus Rüppell, 1842 Species: H. glaber
Binomial name
Heterocephalus glaber Rüppell, 1842

The Naked Mole Rat (Heterocephalus glaber), also known as the Sand Puppy, or desert mole rat, is a very unusual burrowing rodent native to parts of East Africa, predominately South Ethiopia, Kenya, and Somalia. It is the only species currently classified in genus Heterocephalus.

Typical individuals are 8–10 cm long and weigh 30–35 g. Queens are larger and may weigh over 50 g, the largest reaching 80 g. They are well-adapted for their underground existence. Their eyes are just narrow slits, and consequently their eyesight is poor. However, they are highly adapted to moving underground, and can move backwards as fast as they move forwards. Their large, protruding teeth are used to dig. Their lips are sealed just behind their teeth while digging to avoid filling their mouth with soil. Their legs are thin and short. They have little hair (hence the common name) and wrinkled pink or yellowish skin.

Clusters of 20 to 300 animals live together in complex systems of burrows in arid African deserts. They have a complex social structure in which only one female (the queen) and one to three males reproduce, while the rest of the members of the colony function as workers. Like bees (and unlike many ants), the workers are divided along a continuum of different worker-caste behaviors instead of discrete groups^[1]. Some function primarily as tunnelers, expanding the large network of tunnels within the burrow system, and some primarily as soldiers, designed to protect the group from outside predators.

The relationships between the queen and the breeding males may last for many years. A behaviour called reproductive suppression is believed to be the reason why the other females do not reproduce, meaning the sterility in the working females is only temporary, and not genetic. Queens live from 13 to 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.

This eusocial organisation social structure, similar to that found in ants, termites, and some bees and wasps, is very rare among mammals. The Damaraland Mole Rat (Coetomys damarensis) is probably the only other eusocial mammal. The naked mole rat is unique among mammals as it is virtually cold-blooded; it cannot regulate its body temperature at all and requires an environment with a specific constant temperature in order to survive.

The tunnel systems built by naked mole rats can stretch up to two or three miles in cumulative length.^[1] The animals feed primarily on very large tubers (weighing as much as 1000 rats) that they find deep underground, through their mining operations, though they also eat their own feces.^[1] A single tuber can provide a colony with a long-term source of food—lasting for months, or even years.^[1]

Respiration plays an important role, because of the limited availability of oxygen within the tunnels. The lungs of this animal are very small and their blood has a very strong affinity for oxygen, increasing the efficiency of oxygen uptake. It has a very low respiration and metabolic rate for an animal of its size, which uses oxygen minimally. In long periods of hunger, such as a drought, the metabolic rate can reduce up to 25 percent.

The skin of naked mole rats lacks a key neurotransmitter called Substance P that is responsible in mammals for sending pain signals to the central nervous system. Therefore, when naked mole rats are cut, scraped or burned, they feel no pain. When injected with Substance P, however, the pain signalling works as it does in other mammals. [1]

[edit] In popular culture

• A naked mole rat named Rufus is featured in the Disney Channel cartoon Kim Possible.
• The Errol Morris documentary Fast, Cheap and Out of Control features a naked mole rat specialist.

[edit] External links

Distribution of the Naked Mole Rat

• Page on the Animal Diversity Web
• A comprehensive article from Cornell University
• Article from Walker's Mammals of the World
• Naked Mole Rat Cam
• Naked Mole Rat
• Brookfield Zoo with photo
• More photos
• Heterocephalus glaber images at bioimages.vanderbilt.edu
• Naked Mole-rats Hold Clues to Human Aging - LiveScience.com