The chameleon is a unique, fascinating animal. They’re capable of changing color and can move their eyes around, giving them panoramic vision. They’re excellent hunters, able to grab prey at lightning speeds with their long tongues. Scientists have wondered how exactly the tongue works. Specifically, no one had ever figured out how the chameleon tongue manages to hold onto the prey item while reeling it back in. Research just published in Nature Physics finally solves the mystery.
In the past, there have been several theories for how the chameleon’s tongue works. Some researchers thought it used suction to grip onto prey, others believed it formed a special kind of bond using a rough surface. No one had actually conducted research to find out for sure until very recently.
Collaboration between scientists in France and Belgium figured it out. They studied various chameleon species and took measurements of the tongue pad. The researchers found that chameleons have special mucus on the tip of their tongue. The mucus is very viscous and gives the tongue the adhesive properties that allow the lizard to hold onto prey. According to the paper, the mucus is over 400 times more viscous than human saliva. This makes the saliva sticky and glue-like.
Now, scientists are wondering how the chameleon loosens the prey from the tongue to swallow it. Future research is probably needed but the authors speculate that they might use a less sticky form of saliva, from somewhere else in the mouth, to degrade the bond. Another possibility is that the sticky mucus wears off after a while on its own. In viscous adhesion, they explain, the bond is strong because of the quick motion as the tongue pulls the prey back. Once the tongue is back in the mouth, the bond may break. All of this research has the potential to help humans develop stronger adhesives and similar products.
Fabian Brau et al. Dynamics of prey prehension by chameleons through viscous adhesion. Nature Physics (2016).