Naked mole-rat
| Naked Mole Rat Temporal range: Early Pliocene - Recent
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| Genus: | Heterocephalus
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| Species: | H. glaber
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| Heterocephalus glaber | |
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. They are 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 East African deserts. They have a complex social structure in which only one female (the queen) and one to three males reproduces. 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.
Respiration plays an important role, because in the tunnels there exists hardly any oxygen. The lungs of this animal are built very small, so therefore they have blood with a very strong affinity for oxygen, which uses oxygen quite efficiently. It has a very low respiration and metabolism rate for an animal of its size, which uses oxygen minimally. In long periods of hunger, such as a drought, this rate can sink 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.
In popular culture
- A naked mole rat named Rufus is featured in the Disney Channel cartoon Kim Possible.
- he Errol Morris documentary Fast, Cheap and Out of Control features a naked mole rat specialist.
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