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Naked mole-rat

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The naked mole-rat (Heterocephalus glaber) is a burrowing rodent of East Africa. It lives in large colonies in which a single female breeds.[1][2][3]

Classification

Naked mole-rats were first collected in Ethiopia and described in 1842, and later found in Somalia and Kenya. Several forms once named from them are now treated as a single species.[4] Heterocephalus belongs to the African mole-rat family, Bathyergidae. It is the earliest genus of the family in the fossil record, and it split off early in the family's history, perhaps 40 to 48 million years ago.[5][6]

Description

Adults are almost hairless apart from scattered sensory hairs, and the skin has no sweat glands. The tail is about half the length of the body.[7] Animals in a colony typically weigh around 32 g where the soil is very hard. Where hard soil also means scarce food they weigh about 20 g, and non-breeders are smaller in colonies where food is scarcer.[8][9] In wild colonies in Kenya, adult females averaged 36.5 g and males 34.1 g.[10]

Naked mole-rats do not keep a steady body temperature: within the range tested, it follows the temperature around them.[3] Huddling groups hold their temperature better than animals on their own.[11]

Colonies

In a study of 14 colonies near Tsavo West in Kenya, colony size ranged from 25 to more than 295, with an average of about 75.[12] Averages of 70 to 80 animals are typical in the wild and in captivity.[13]

Every complete wild colony studied has had only one breeding female. She is usually the longest animal and one of the heaviest, and one to three males breed with her.[1][14] Ovulation is blocked in the females that do not breed.[2] In captivity a breeding female can remain the colony's only breeder for more than a decade, and many non-breeders never breed in their lives.[13]

The non-breeders share the work according to body size. Small animals do most of the carrying of food and nest material and the clearing of debris. Large animals dig and defend the colony against snakes and other colonies.[15] Body sizes do not fall into separate physical castes.[14] Naked mole-rats can be highly inbred. Successful dispersal from a colony is rare.[16]

Breeding

Litters are born all year round. In the wild an average of about 9.7 young per litter were weaned. In captivity pregnancy lasts 70 to 80 days, and litters of up to 27 have been recorded.[17][18] Pups are fairly helpless at birth. They start eating solid food at about two weeks and begin leaving the nest at about three weeks.[9] One breeding female lost up to 16 per cent of her body mass while feeding her young.[19]

Burrows and food

Colonies dig large burrow systems. One colony of about 87 animals at Kamboyo occupied an area of about 440 by 240 m. Each year it threw up 400 to 500 molehills, moving 3,600 to 4,500 kg of soil and digging 2.3 to 2.9 km of new tunnel.[20] Shallow foraging tunnels lie beneath the molehills, and wider main tunnels run at 50 cm or deeper, leading to deep nest chambers. The air in the burrows is about 90 per cent humid.[21]

Naked mole-rats feed mainly on the swollen underground parts of plants, such as tubers, bulbs and roots.[22][23][3] Gut microbes digest the cellulose, and the animals eat their own droppings.[11] They get all the water they need from their food and do not drink.[3]

Status

Animal Diversity Web lists the naked mole-rat as Least Concern on the IUCN Red List.[23]

See also

References

  1. ↑ 1.0 1.1 Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 83 (ch. 3, Jarvis and Bennett). ISBN 9781400887132.
  2. ↑ 2.0 2.1 Faulkes, Chris G.; Bennett, Nigel C. (2007). "African Mole-Rats: Social and Ecological Diversity". In Wolff, Jerry O.; Sherman, Paul W. (eds.). Rodent Societies: An Ecological and Evolutionary Perspective. University of Chicago Press. p. 436. ISBN 9780226905365.
  3. ↑ 3.0 3.1 3.2 3.3 "Naked mole-rat". Smithsonian's National Zoo and Conservation Biology Institute.
  4. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. pp. 68–69 (ch. 3, Jarvis and Bennett). ISBN 9781400887132.
  5. ↑ Faulkes, Chris G.; Bennett, Nigel C. (2007). "African Mole-Rats: Social and Ecological Diversity". In Wolff, Jerry O.; Sherman, Paul W. (eds.). Rodent Societies: An Ecological and Evolutionary Perspective. University of Chicago Press. p. 428. ISBN 9780226905365.
  6. ↑ Faulkes, Chris G.; Bennett, Nigel C. (2007). "African Mole-Rats: Social and Ecological Diversity". In Wolff, Jerry O.; Sherman, Paul W. (eds.). Rodent Societies: An Ecological and Evolutionary Perspective. University of Chicago Press. p. 429. ISBN 9780226905365.
  7. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 74 (ch. 3, Jarvis and Bennett). ISBN 9781400887132.
  8. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 77 (ch. 3, Jarvis and Bennett). ISBN 9781400887132.
  9. ↑ 9.0 9.1 Faulkes, Chris G.; Bennett, Nigel C. (2007). "African Mole-Rats: Social and Ecological Diversity". In Wolff, Jerry O.; Sherman, Paul W. (eds.). Rodent Societies: An Ecological and Evolutionary Perspective. University of Chicago Press. p. 434. ISBN 9780226905365.
  10. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 111 (ch. 4, Brett). ISBN 9781400887132.
  11. ↑ 11.0 11.1 Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. pp. 77–78 (ch. 3, Jarvis and Bennett). ISBN 9781400887132.
  12. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 135 (ch. 4, Brett). ISBN 9781400887132.
  13. ↑ 13.0 13.1 Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 384 (ch. 13, Jarvis). ISBN 9781400887132.
  14. ↑ 14.0 14.1 Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 134 (ch. 4, Brett). ISBN 9781400887132.
  15. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 319 (ch. 10, Lacey and Sherman). ISBN 9781400887132.
  16. ↑ Faulkes, Chris G.; Bennett, Nigel C. (2007). "African Mole-Rats: Social and Ecological Diversity". In Wolff, Jerry O.; Sherman, Paul W. (eds.). Rodent Societies: An Ecological and Evolutionary Perspective. University of Chicago Press. p. 435. ISBN 9780226905365.
  17. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 98 (ch. 4, Brett). ISBN 9781400887132.
  18. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. pp. 114, 116 (ch. 4, Brett). ISBN 9781400887132.
  19. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 404 (ch. 13, Jarvis). ISBN 9781400887132.
  20. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. p. 146 (ch. 5, Brett). ISBN 9781400887132.
  21. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. pp. 142, 149, 152, 155 (ch. 5, Brett). ISBN 9781400887132.
  22. ↑ Sherman; Jarvis; Alexander, eds. (2017). The Biology of the Naked Mole-Rat. Princeton University Press. pp. 139–140 (ch. 5, Brett). ISBN 9781400887132.
  23. ↑ 23.0 23.1 Hagan, K. (2013). "Heterocephalus glaber". Animal Diversity Web. University of Michigan.
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