The tongues of frogs and toads are amazing. These animals can catch an insect with their sticky tongues faster than a human can blink.
Some species can even catch larger animals, like mice and birds. No human device can match the grabbing speed of a frog's tongue or the special chemical properties of its saliva.
The frog's abilities have to do with the physical properties of its tongue and the chemical properties of its saliva. A frog's tongue is ten times softer than a person's. When it hits its victim, it acts like a shock absorber, to keep the prey from bouncing off. The softness also allows it to fit itself to the complex shape of an insect's body.
Incredible Frog Spit
The frog's saliva has to be really sticky given the high speeds involved, as well as the prey's ability to put up a struggle. It can do fifty times the adhesive work of the best human-made synthetic polymers. Even more impressively, its properties are quickly reversible.
When the saliva first comes in contact with the insect, it's almost as thin as water and can fill the bug's crevices for a good hold. When the tongue snaps back, the saliva becomes thicker than honey and exerts a firm grip. When tongue and prey are inside the frog's mouth, the saliva turns watery allowing the animal to swallow its unfortunate meal.
Understanding how a frog's tongue works can help scientists develop all sorts of new adhesives and robotic devices.
Thank you to Stanislav Gorb of Kiel University in Germany for reviewing this episode!
Sources And Further Reading:
- Alexis C. Noel et al. 2017. Frogs use a viscoelastic tongue and non-Newtonian saliva to catch prey. J. R. Soc. Interface 14 (127): 20160764; doi: 10.1098/rsif.2016.0764
- Devlin, Hannah. "Special spit is the secret of uniquely sticky frog tongues, study reveals." The Guardian. January 31, 2017. Accessed July 10, 2017.
- Davis, Josh. Reversible saliva is what makes a frog's tongue so sticky. IFL Science. February 2, 2017. Accessed July 10, 2017.