Phil Budd (of the Southampton Natural History Society) recently gave me a dead mole Talpa europaea, and here it is. It isn’t the first mole for my collection: I have another one that I skeletonised long ago. Moles really are amazing. Their forelimb and pectoral anatomy has to be seen to be believed, and is so modified relative to what’s typical for mammals that even some experienced people struggle to identify elements of the mole forelimb skeleton. The short-shafted humerus sports immense expansions and crests for hypertrophied musculature, the sternum is highly elongate and deeply keeled, and the massively broad hand includes a huge sickle-shaped sesamoid and gently curved, stout claws (Yalden 1966, Whidden 2000, Sánchez-Villagra et al. 2004)…
Mole teeth are pretty neat too. The upper canine is particularly large and unusual in being double-rooted. In the lower jaw, the canine is so small that it looks pretty much the same as the three small incisors, but the first premolar is enlarged and caniniform [see skull below: from skullsite]. The molars have large pointed cusps where the crests on top of the teeth (the ectolophs) have a dilambdodont configuration: this is where the metacone and paracone form the lower ‘valleys’ of a W shape and the metastyle, mesostyle and parastyle form the three ‘peaks’ (the metacone and paracone are on the lingual side of the molar, and the metastyle, mesostyle and parastyle are on the labial side). Shrews and some bats are also dilambdodont. Talpa europaea is pretty small: head-body length is 11-15 cm, tail is 2-4 cm long. It’s one of about nine Talpa species; they occur from western Europe to Siberia, but the systematics of this group is controversial. Talpids – ‘true moles’ – also occur in North America, and they’re not all fossorial specialists. Some are more shrew-like and only semi-fossorial, and some (the desmans) are amphibious. I am resisting the urge to elaborate.
Here in Britain there is a lot of conflict between people and moles. It seems that many people enjoy maintaining vast, flat, barren spaces covered by nothing but grass. Moles are good at screwing with this tidiness – Macdonald (1995) reported a field covered by 7380 molehills per hectare. This adds up to 64500 kg of displaced soil amounting to 40 cubic metres, or to 25 km of tunnels. Besides the aesthetic damage molehills do to golf courses and so on, molehills encourage weeds and can also contaminate silage with the bacterium Listerella. Apparently, King William of Orange died in 1702 after falling off his horse, and the horse had stumbled over a molehill. This ended William’s plans to subjugate the Scottish clans.
Moles are highly territorial and, mostly in June, juveniles disperse from their parental territories and end up getting into all kinds of japes and scrapes. They get eaten by raptors, cats and dogs, and end up dead on roads a lot. And I need to stop there, but there’s so much more to say. Oh well…
Refs – -
Macdonald, D. 1995. European Mammals: Evolution and Behaviour. HarperCollins, London
Sánchez-Villagra, M. R., Menke, P. R. & Geisler, J. H. 2004. Patterns of evolutionary transformation in the humerus of moles (Talpidae, Mammalia): a character analysis. Mammal Study 29, 163-170.
Whidden, H. P. 2000. Comparative myology of moles and the phylogeny of the Talpidae (Mammalia, Lipotyphla). American Museum Novitates 3294, 1-53.
Yalden, D. W. 1966. The anatomy of mole locomotion. Journal of Zoology 159, 55-64.