Why do cats have scratchy tongues?

The language of cats hide several curiosities that you may not know. Anyone who has had contact with cats and has licked their hand will have realized that it scratches, even sometimes, and can even cause damage, if the licking is insistent.

This is because the surface of the cat’s tongue has structures called filiform papillae , which are sharp, curved, backward-facing keratin spines. The function of these papillae is still a mystery.

Cats have sweat glands only on the pads, so sweating will take place through that means. Grooming allows them to lower their body temperature. In fact, it has been estimated that a third of the water vapor that evaporates comes from this practice. We must know that it is not the only animal in nature that does it, although felines are the only ones that have these spicules on their tongues.

Formerly these spicules were described as conical and solid structures. In 2018, several researchers described these papillae as conical with an opening at the tip that allows the cat to spread saliva through its fur.

In the domestic cat, these openings have a capacity of 0.014μL of saliva, which corresponds to a total of 4.1μL among the 290 papillae, which to get an idea is one tenth of a drop of a dropper drop.

For a cat to have well-groomed fur, it needs to reach the skin with its papillae in order to groom the deepest layer of hair well. For this reason, there are different breeds that are easier to groom themselves than others.

The common European cat, having a lower layer of hair, will be able to groom itself better than, for example, a Persian. Persian cats, having a coat with longer hair, have more difficulty grooming, so they will be cats that need more hair care from us.

What is the cat’s tongue for?

One of the functions of the tongue, as we have seen, is to lower its body temperature.

The tongue also has these functions:

• preen The papillae of the tongue are used to clean the hair, brush it, remove dirt and possible fleas. In fact, it has been seen that cats that for different reasons stop grooming themselves are more likely to have fleas.
  This grooming is not done solely for hygiene and cleanliness, but to avoid different odors in their hair that can give them away when hunting.
  This natural behavior can be altered for different reasons, and an increase or decrease may appear, even elimination of it.
  This lack of grooming can in turn cause skin injuries if there is the formation of knots, for example. While excessive grooming, due to itching or pain, for example, can cause hair loss or alopecia in different areas, causing not only dermatological problems, but also digestive disorders due to excess hair consumption.

• Tactile communication with other cats in the same social group . This communication is done by licking another cat, usually around the face, head, and neck. This positive licking between cats in the same social group helps maintain the scent of the group and strengthen bonds.
  There is still a lot to investigate around feline behavior, since this grooming between cats can sometimes end in a negative way, or alternate between the two situations. Being able to see that the cat that is being groomed does not enjoy the moment, or even the one that does it behaves aggressively.

• To drink. Cats use surface tension to extract water during licking, and thus take the water to drink cleanly, without splashing or getting their face or whiskers wet.

• to eat These rough spines allow them to separate the meat from the bone when eating. They work as a tool to clean the bones of their prey and thus be able to make the most of the muscle of their catch.

• Relaxation . When the spines come into contact with the skin, they produce a movement similar to a massage that produces a relaxing effect on the cat.
  The cat’s tongue and its functions continue to be one of the most consulted curiosities by lovers of these felines.

Referencias

Noel, A. C., & Hu, D. L. (2018). Cats use hollow papillae to wick saliva into fur. Proceedings of the National Academy of Sciences, 115(49), 12377-12382.

Noel, A., Martinez, A., Jung, H., Tsai, T. W., & Hu, D. (2016, November). Cat tongue Velcro. In APS Division of Fluid Dynamics Meeting Abstracts (pp. L1-008).

Reis, P. M., Jung, S., Aristoff, J. M., & Stocker, R. (2010). How cats lap: water uptake by Felis catus. Science, 330(6008), 1231-1234.