Topic: Anointing in mammals
The strategy of anointing the body with the scent of a more dangerous animal has evolved independently several times, including in rodents, hegdehogs and tenrecs.
One way to protect yourself is to slap on the scent of some very dangerous animals, so that odds are they will leave you alone. This strategy, with a role in defence and possibly other functions such as sexual attraction, has evolved independently several times, including in rodents, hegdehogs and tenrecs.
(i) Ground squirrels
Ground squirrels are rodents that, by way of defensive anointing, are known to chew bits of rattlesnake skin and then apply it to their bodies, especially the tail and flanks. Of course, one needs to consider alternative explanations to it being an anti-predatory camouflage such as to control fleas, etc, but some sort of olfactory camouflage seems most likely. Recall also that these squirrels can make infrared beacons to advise snakes that employ this sensory modality that they have been spotted.
(ii) Other rodents
Squirrels are not the only rodents to apply snake scent. Anointing the body with snake-derived scents is alos known to occur in Siberian chipmunks (Tamias sibericus) and the Rice-field rat Rattus argentiventer of South-East Asia.
Hedgehogs are insectivores, and so not particularly close to the rodents, and they have taken self-anointing to new heights as they plaster their bodies with saliva laced with toad venom (derived from the toad’s skin; the hedgehog eats the rest) and a long list of other substances. They can provoke a strong reaction in laboratory tests, but the principal role may be more to do with sexual attraction(!!) than defence.
The tenrecs are a very interesting group of Madagascan insectivores. As is well known some species (e.g. Echinops telfairi and Setifer setosus) have striking similarities to the hedgehogs (although they are not closely related), and remarkably these not only include spineyness (as their generic names suggest), an ability to enrol (useful), but also self-anointing assisted by copious amounts of saliva.
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Map of Life - "Anointing in mammals"
September 21, 2020