Naked Mole-rat

Heterocephalus glaber

Order: Rodentia

Husbandry Information

Housing Requirements

  • Naked mole-rats have a natural instinct to tunnel and are able to chew through most materials over time. They may be contained in glass or plastic-walled cylinders (like clear PVC pipes) or cubes (like glass tanks) as long as they can’t get their teeth around any edges and chew through. When housing this species in a hydrostone-lined chamber, as in many naturalistic exhibits, keepers should expect to perform periodic repairs to the hydrostone.
  • Naked mole-rats should be kept in a warm room. The temperature inside the colony’s chambers should be between 82-87°F for optimum health. Naked mole-rats evolved without the ability to thermo-regulate and will fail to thrive if kept too cold. Humidity should be around 40% to avoid dry skin issues; chambers may be misted with water if necessary.
  • Can be very sensitive to sounds and vibrations. May be kept in a quiet area or gradually acclimated to more activity through exposure to voices, music, etc. Survivorship of pups can be promoted by decreasing disturbances after birth and slowly returning to a normal husbandry routine over the next month to 6 weeks.
  • Olfaction is very important in this species and colony members identify each other through a shared odor. Chambers should be spot-cleaned daily with water but soap should only be used occasionally and care should be taken to maintain the colony’s scent through partial substrate changes, cleaning one surface at a time, etc. Chemicals should never be used in hydrostone chambers.

Diet Requirements

  • Naked mole rats are herbivores, eating tubers and roots in the wild. The National Zoo provides them with a variety of root vegetables (turnip, beet, sweet potato, carrot), as well as corn, green beans, and leafy greens. Biscuits are included in their diet.
  • Naked mole rats do not drink water and should never be given free-standing water. They are given apple in their diet as a moisture boost.
  • An appropriate balance of calcium and phosphorus is important for long-term health in this species. They should eat foods high in complex carbohydrates rather than rapidly metabolized sugars. Rice cereal is a good maintenance food.
  • Coprophagy is normal for this species.

Veterinary Concerns

  • The teeth of naked mole rats should be monitored for malocclusion. Simple veterinary procedures can correct this problem.
  • Teeth may fall out in older animals. Select food for these animals may be “cooked” in order to soften hard root vegetables.
  • These animals are intensely social and should never be isolated for more than an hour from the colony. If it is necessary to remove a naked mole-rat from the colony for extended veterinary treatment, that individual should be housed with at least two worker mole-rats at a time. These workers should be switched out about twice a day and rotated back through the colony to maintain social integration. Substrate may also be exchanged between the colony and the individual under treatment to maintain olfactory communication and facilitate eventual reintegration into the colony.

Notes on Enrichment & Training

  • Enrichment for naked mole rats can relate to their natural burrowing and foraging behavior. The National Zoo often stuffs their diet into tunnels forcing the naked mole rats to excavate their food. Other novel items, such as cardboards, paper towels, and hay can be used to jam tunnels; naked mole rats are seen carrying these items throughout their exhibit for several hours after placement.
  • Naked mole-rats are motivated to create a “nest” of materials such as hay, browse. or paper. Workers can be occupied for long periods shredding nesting material and moving it to their nest chamber.
  • This species has a strong instinct for chewing and should be given items such as sticks and clumps of hydrostone to chew. This will also reduce wear and tear on colony chambers.

Other

Colony or Breeding Management

 

Individual Identification

 

Programmatic Information

Transportation

Temperature Guidelines

 

Crating:

Tips on Presentation

  • Take at least three individuals out for presentation at a time to avoid stress and loss of body heat. Bringing out an assortment of workers and soldiers will also help to illustrate the eusocial nature of the species.
  • We typically present this species indoors and are careful not to expose them to bright sunlight, loud noises, or temperatures below 70 degrees.
  • We take our naked mole-rats out for presentations in a critter carrier or rubbermaid tub on a rolling cart for most groups. Small groups can be seated around the carrier on the floor for a closer look.
  • Naked mole-rats have devoted fans. We frequently take interested guests behind the scenes for impromptu “Memorable Moment” tours so that they can see the animals up close. We sometimes allow limited numbers of guests to touch these animals on their backs or hindquarters.

Touching Techniques

Tips on Handling

  • Naked mole-rats can easily be desensitized to handling through regular handling during the daily husbandry routine. They may bite but do so very rarely.
  • Naked mole-rats can back up faster than they can move forward so care should be taken to avoid dropping one if it makes a sudden move. We typically hold ours within a foot or two over a container like a critter keeper during presentations as a precaution.
  • Can be scruffed by the loose skin behind their necks or picked up by loose skin anywhere along their backs. Once they are accustomed to handling, they appear calmer with their bodies supported firmly but gently in the hand.

 

Potential Messaging

  • Endemic to hot, arid regions of Kenya, Somalia, and Ethiopia.
  • Desert and Dryland species have specific adaptations for the temperature and water availability in their natural habitat and may not be able to adjust to the drying effects of climate change. Hotter conditions promote wildfires. More extreme drought conditions kill plants that hold the soil in place and occasional extreme rain events wash that soil away preventing them from growing back in a process called desertification. Greenhouse gas emissions from burning fossil fuels contributes to climate change by trapping heat in the atmosphere. Please ask guests to walk, bike, or take public transportation when possible and to reduce their use of fossil fuels when they do drive by buying a fuel economic car, carpooling, combining errands, and keeping vehicles properly tuned up and their tires properly inflated. At home and work, purchase Energy Star appliances, turn off lights when they are not in use, and use heaters and air conditioners sparingly. The principles of reduce, reuse, and recycle will also help by decreasing greenhouse gas emissions involved with the manufacture and disposal of unnecessary goods.
    http://www.unep.org/geo/gdoutlook/045.asphttp://www.epa.gov/climatechange/wycd/https://biomesfirst09.wikispaces.com/Desert+Conservationhttp://www.wildlifeadaptationstrategy.gov/pdf/Desert_Ecosystems_Paper.pdf
  • Naked mole rats are the poster children for adaptation. They have a number of unique attributes that help them succeed in a difficult environment.

Acquisition Information

Houston Zoo has a breeding colony of naked mole-rats and frequently has individuals that could be sent to other institutions.

Comments from the Rating System

  • National Zoo: Fan favorite with lots of information to discuss with groups, especially in regards to mammal characteristics.
  • Pittsburgh Zoo: They are very small for many programs and are displayed in a container only for programs.

Natural History Information

Range and Habitat

Naked mole rats are found in semiarid grassland habitats in Eastern Africa, specifically in the countries of Somalia, Ethiopia, and Kenya. They create underground burrows and rarely appear above ground.

Physical Description

 

  • Naked mole-rats spend their lives below the surface of the ground and have poor vision. They are very sensitive to vibration and have touch-sensitive whiskers on their face and bodies that help them to navigate their tunnels.
  • Naked mole-rats use their teeth to dig through their earth, creating chambers and tunnels. They have the strongest jaw muscles of any mammal their size. They have 20% of their musculature in their jaw – the same amount of musculature in a human being’s legs.
  • Unlike other mammals, naked mole-rats are unable to maintain a constant body temperature when environmental temperatures change more than a few degrees.
  • Naked mole rats are nearly blind; they have no need to see underground and their eyes are almost completely useless. They can see the difference between light and dark, but they probably can’t make out any forms or shapes.
  • Researches have found that a large portion of the naked mole rat’s brain is devoted to their front teeth. Naked mole rats probably use their teeth as a sensory organ due to their lack of vision.

 

 

Life Cycle

  • Naked mole-rats are long lived. Captive specimens have lived into their late 20’s.
  • During the queen’s first few pregnancies, her lumbar vertebrae elongate, creating more room in her body for gestation. The naked mole rat queen is the only mammal whose bones grow after adulthood.
  • Litters commonly number in the high teens. When a queen first emerges, she can have 10-15 babies at a time, a similar number to other rodents, such as mice or rats. Once she reaches her maximize size, she can have up to 30 babies a litter – the most babies per litter of any mammal!

Behavior

 

  • This species is eusocial like bees and ants. The “queen” is the only female breeder. The rest of the colony is divided into larger soldiers who defend the colony from intruders and smaller workers who find food and care for young.
  • Any female can become the queen. Females will challenge the queen and attempt to kill her. If a queen is dethroned, the new female will become queen. The reigning queen keeps her position if she can thwart the attacks by other females in her colony.
  • This species lives in chambers under the ground. Some chambers are specifically used for food storage, nests, or latrines.
  • Naked mole rats will roll around in their toilet chambers to take on the odor of the colony. This helps mole rats determine which animals are from their own colony. They will fight other mole rats that do not share their odor.

 

 

Threats and Conservation Status

The naked mole rat is listed as a species of least concern by IUCN.
Typical threats to naked mole rats include predators (snakes), agriculture, and development.

Did you know…

  • There are at least 27 species of mole-rat. They are neither moles nor rats but are more closely related to guinea pigs and chinchillas.

Photographs

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NMR chamber game with zoo camp at HZI

 

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A trio of naked mole rats during a photoshoot at the National Zoo.

Documents

Contributors and Citations

Top Photo: Workers, soldiers and young at Houston Zoo