You might know that the cat’s tongue is covered with around 290 tiny but prominent backward facing spines (papillae) made of keratin. Our nails are made of keratin. And cats groom themselves for about 2.4 hours daily.
Recent research, using CT scans, discovered that the part of the cat’s papillae are hollow. They researched several species of cat: tiger, lion, domestic cat, bobcat, puma and snow leopard.
Cavity in Spines
The hollowed out spines carry saliva in to the deep recesses of the cat’s fur or efficient cleaning. The process also cools the cat.
The spines are about 2mm in length. There is a U-shaped cavity at the tip which fills with a tiny but significant amount of the cat’s saliva, 4 microliters to be precise. This saliva is deposited deep into the fur right down to the skin. The spines or spikes of the tongue are attached to the tongue with a hinge -like mechanism. These allow the spikes to drive through fur in a “a low-drag configuration” until they hit a tangle.
“The papillae…feature a hollow cavity at the tip that spontaneously wicks1 saliva from the mouth and…releases it onto hairs”.
The grooming action cools the cat because it removes heat from the cat in the saliva which is deposited in the fur where it evaporates. Except for their paws domestic cats don’t have sweat gland so this form of heat loss is important. Note: cats also cool themselves via panting which is cooling by the evaporation of saliva on the tongue.
The researchers believe that their study could inspire businesses to create a more efficient cleaning process using robotics and ‘biologically inspired technologies for cleaning and depositing fluids into…arrays of flexible filaments’.
They created an experimental brush using the findings which is shown in the video. It was made with a 3-D printer.
Some extra info added later
We are told that the tongue-inspired grooming brush requires as little as half of the force of a traditional brush to be applied when pulled through here.
Prof Hu (the lead researcher of the Georgia Institute of Technology in Atlanta) said that L’Oreal had contacted him to discuss his findings. It appears that the research could lead to an improved hairbrush to potentially be marketed by L’Oreal.
The tongue acts like a loofah and a sponge at the same time. The patient application has been filed for their brush. They claim that hairbrush technology has been moribund i.e. dormant and not progressive for a long time.
The earliest known comb is believed to date from 8000 BC. It was carved from animal born in Syria. The basic shape of the comb is not changed since.
The researchers also believe that a cat’s tongue could help in the application of fluids or in the cleaning of carpets or in the application in medicine.
1. To ‘wick’ means to absorb or drain like a wick. A wick is a bundle of fibres which, through a capillary action, draws up fluids.
2. Study: Cats use hollow papillae to wick saliva into fur – by Alexis C. Noel and David L. Hu, published on the PNAS.org website.