Instead (look at the molecular phylogeny above, from Seney et al. (2009), CC.īut this never made sense given that the Naked mole-rat is not nested within Cryptomys or Fukomys. B and C by Sharry Goldman D by Radim Šumbera. The images at right show (B) Fukomys, (C) Heliophobius, and (D) Heterocephalus. And, yes, the colonies are huge relative to what you might guess: they average 80 individuals, and can consist of as many as 300.Īt left, a molecular phylogeny of bathyergid mole-rats - note how old the Heterocephalus divergence is, and how Heterocephalus is the sister-taxon to the rest of the clade.
This mention of coloniality and a single breeding pair will of course remind you of the eusocial system present in Naked mole-rats, whereby an especially big Queen is the lone breeding female in the relatively enormous colony, the individuals of lower castes having a suppressed reproductive ability and living a life where all they do is work: they maintain the burrows, care for the babies and so on. Some of the common mole-rat species are colonial (some others are solitary), the non-breeding individuals collecting roots, excavating tunnels, and caring for the young of the single breeding pair. In addition to Heterocephalus, there’s Cryptomys (containing the seven or so species of common mole-rat), Fukomys (named for a set of species included within Cryptomys until 2006), Georychus (the Cape mole-rat), Heliophobius (the Silky mole-rat), and Bathyergus (the dune mole-rats). None of the several genera are especially familiar or well known. The burrows they construct can be absurdly long: people have discovered common mole-rat burrow systems exceeding 1 km in length, and some Naked mole-rat burrows are over 3 km long ( Jarvis 2001). Several species store plant parts in special burrow chambers and some will only eat part of a root or geophyte, apparently deliberately leaving it to recover and regenerate such that it can be exploited over the long term. Mole-rats are herbivorous, and most species rely on geophytes (storage organs) and roots, though grasses, herbs and occasionally invertebrates and even other rodents are eaten by some species too. The rather boldly marked Cape mole-rat or blesmol ( Georychus capensis) in life.
Long claws are typical, as is very short, velvety fur of the sort present widely in subterranean mammals ( Heterocephalus being the obvious exception). The incisors in the lower jaw are able to move independently (is this unique among mammals?), their long roots occupying a huge portion of the skull’s interior and adding to its great strength (“a steel rod, a square millimetre in section, only penetrated when a weight of 3 kg was applied – this is equivalent to about 8cwt per sq in” ( Hanney 1977)). Prominent grooves are present on the incisors of some species. Their large white incisors are exposed even when the mouth is closed, the lips actually closing behind the incisors.
Images from the Tet Zoo textbook project.īathyergid mole-rats are compact, short-tailed rodents with tiny eyes and near-invisible ears. The groups shown here are cane rats, dassie rats, gundis, Old World porcupines, African mole-rats and caviomorphs (represented by the chinchillid Lagidium).
Hystricomorph/ctenohystrican/entodacryan rodent montage.
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