Frog tongues are covered with a shear-thinning fluid that can modulate from sticky to not sticky based on the force applied.
Frogs use a sheer thinning fluid on their tongues to quickly capture prey and release it in their mouths. This fluid can change from sticky and viscous to thin and not sticky simply by changing the force's direction. This means the fluid can be sticky when needed and not sticky all other times without leaving residues. Fluids like this and the mechanisms for employing them can be applied in soft robotics, manufacturing, agriculture, and aviation.
