Grip, grab and groom: The biomechanics of frog and cat tongues

Abstract

The tongue is a soft muscle capable of grabbing different prey items through variations in tongue roughness and saliva coatings. In this thesis, I present two extremes of tongue surfaces: smooth frog tongues coated in sticky saliva, and rough feline tongues covered in rigid spiny microstructures. Frogs use a combination of their viscoelastic saliva and soft tongue tissue to adhere to and retract prey in less than 0.1 seconds. I conduct a subsequent study on 6 species of feline tongues, from lions to tigers to housecats. The hollow, rigid spines on the cat tongue aid in cleaning and detangling of fur by distributing saliva. The spines are anisotropic in direction, allowing for easy removal of fur from the tongue. Using CT scans of the cat tongue spines, I develop a flexible, 3D-printed cat tongue mimic, which is found to de-tangle fur with less force than a standard hairbrush. Lastly, an overview is provided of other biofluids, focusing on the effects of wetting.