Rub a Dub Dub: Ring-Tailed Coatis Wash Up With Soap

Nothing feels quite as good as getting clean with a nice soapy lather – and apparently, ring-tailed coatis (Nasua nasua) agree. A new study details observations of and experiments with a group of the raccoon-like animals that have taken to rubbing themselves with soap and laundry detergent.

This behavior, sometimes called self-anointing, is not uncommon in the animal kingdom. Animals that engage in it usually apply substances with pungent smells or noxious secretions, and one function is believed to be self-medication. Several primate species, such as capuchin monkeys, lemurs, and owl monkeys, self-anoint with substances ranging from fruits and leaves to millipedes. The millipedes they use secrete compounds that repel pests like mosquitoes and ticks. Animals will even use human-introduced substances to self-anoint: researchers observed captive capuchin monkeys rubbing onions, laundry soap, and limes onto their skin and fur as antiseptics and insect repellents.

Coatis are relatives of the raccoon that live in Central and South America. Free-ranging coatis have been reported to rub tree resin and millipedes over their bodies, probably to repel parasites. But this new study is the first description of coatis using soap to self-anoint.

Researchers from Brazil and Colombia noticed that a group of free-living coatis behind a tourist complex on an island off of Brazil were taking advantage of the cleaning supplies left behind by human visitors. During two visits to the island, the researchers recorded all occurrences of spontaneous washing behaviors. Additionally, they conducted five experimental sessions in which laundry products (pieces of bar soap and a bucket with laundry soap diluted in water and full of foam) were deposited near the coatis to see what they would do.

The researchers observed 15 spontaneous self-anointing events with soap. The coatis used soap, suds (resulting from chewing on bar soap), or foam (produced by mixing the laundry soap with buckets of water) to apply soap to themselves, and sometimes onto each other. In all the experimental sessions, one to three animals performed soap-anointing behavior.

Coatis rubbed cleaning substances onto their fur, focusing mostly on the tail and genital regions. Self-anointing sessions lasted from a few seconds to nearly five minutes. (Watch a video of coatis self-anointing with soap here).

The researchers suggest that these coatis may be applying soap as a form of self-medication or health maintenance. The coatis focused their attention on their genitals and tails, moist and warm areas that are ideal for bacterial and fungal growth. Cleaning with soap could help prevent microorganism infection, relieve irritation from such infections, and repel parasites like ticks.

This behavior has persisted for more than 10 years in this particular group of coatis. It is likely that close contact with humans and easy access to soap inadvertently left outside led to this innovation, helped along by coatis’ behavioral flexibility and motivation to explore new situations. Coatis are social and long-lived animals, so it seems probable that soap-anointing behavior is being socially transmitted across generations within the group from older to younger individuals. The result is a unique culture of self-medication in this coati group.

Reference: Gasco, A. D. C., Pérez-Acosta, A. M., and Monticelli, P. F. (2016). Ring-tailed coatis anointing with soap: a new variation of self-medication culture. International Journal of Comparative Psychology 29.