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Naked Mole Rat

2007 Schools Wikipedia Selection. Related subjects: Mammals

   How to read a taxoboxNaked Mole Rat

                    Fossil range: Early Pliocene - Recent

                    Conservation status

   Least Concern
                 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 burrowing rodent native to parts of
   East Africa. It is notable for its eusocial lifestyle, nearly unique
   among mammals, and for a highly unusual set of physical traits that
   enables it to thrive in a harsh, underground environment; including a
   lack of pain sensation in its skin, and a nearly cold-blooded
   metabolism.

Taxonomy

   The Naked Mole Rat (Heterocephalus glaber), also known as the Sand
   Puppy, or Desert Mole Rat, is the only species currently classified in
   genus Heterocephalus.

Physical description

   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 mouths with soil. Their legs are thin and short.
   They have little hair (hence the common name) and wrinkled pink or
   yellowish skin.

   The naked mole rat is well adapted for the limited availability of
   oxygen within the tunnels that are its habitat: its lungs are very
   small and its 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, thus using oxygen minimally.
   In long periods of hunger, such as a drought, its metabolic rate can
   reduce up to 25 percent.

   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 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.

Ecology and behaviour

Distribution and habitat

   Distribution of the Naked Mole Rat
   Distribution of the Naked Mole Rat

   The naked mole rat is native to the drier parts of the tropical
   grasslands of East Africa, predominantly South Ethiopia, Kenya, and
   Somalia

   Clusters averaging 75-80 live together in complex systems of burrows in
   arid African deserts. The tunnel systems built by naked mole rats can
   stretch up to two or three miles in cumulative length.

Social structure and reproduction

   Naked mole rats 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. As in certain bee
   species, the workers are divided along a continuum of different
   worker-caste behaviors instead of discrete groups. 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 that the
   infertility 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.

Diet

   Radicivores, the naked mole rats feed primarily on very large tubers
   (weighing as much as 1000 times the body weight of a typical mole rat)
   that they find deep underground, through their mining operations,
   though they also eat their own feces. A single tuber can provide a
   colony with a long-term source of food—lasting for months, or even
   years.

Conservation status

   Not threatened. Despite their tough living conditions, naked mole rats
   are quite widespread and numerous in the drier regions of East Africa.

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.

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