Golden moles
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Eremitalpa |
Golden moles are small, insectivorous burrowing mammals native to southern Africa. They bear a remarkable resemblance to the marsupial moles of Australia, so much so that, the marsupial/placental divide notwithstanding, they were once thought to be related!
Golden moles live almost exclusively underground. Like several other burrowing mammals with similar habits, have short legs with powerful digging claws, very dense fur that repels dirt and moisture, and toughened skin, particularly on the head. They retain eyes but they are non-functional and covered with skin and fur, the ears are just tiny openings, and, like the marsupial moles, they have an enlarged leather-like pad to protect their nostrils.
They range in size from about 8 to about 20 cm. They have muscular shoulders and an enlarged third claw to aid digging on the forelimbs, with no fifth digit and vestigal first and fourth; the hind feet retain all five toes and are webbed to allow efficient backward shoveling of the soil loosened with the front claws.
Like most of the mammals that originated in Gondwana, golden moles used to be regarded as rather 'primitive' creatures: their low resting metabolic rate and their ability to switch off thermoregulation when inactive, however, are no longer regarded as indications that golden moles are undeveloped 'reptilian mammals', but rather as essential adaptations to a harsh climate. By going into a torpor when resting or during cold weather, they conserve energy and reduce their need for food. Similarly, they have developed particularly efficient kidneys and most species do not need to drink water at all.
Of the 21 species of golden mole, no less than 11 are threatened with extinction. The primary causes are sand mining, poor agricultural practices, increasing urbanisation, and predation by domestic cats and dogs.
As with many groups, the classification of the golden moles is undergoing an upheaval at present in the light of the flood of new genetic information becoming available. They have traditionally been listed with the shrews, hedgehogs and a grab-bag of small, difficult-to-place creatures as part of the order Insectivora. Some authorities retain this classification, at least for the time being. Others group the golden moles with the tenrecs in a new order which, unhelpfully, may be known as either Afrosoricida or Tenrecomorpha. For simplicity, the former is used here.