Scientists have made a new and exciting discovery which may change the view on how a frog captures its prey.
The researchers have found that the tongue of a frog changes from watery thin to thick and sticky as the amphibian pulls in flies and insects conveniently into its mouth.
The tongue is also quite soft in nature. It is said to be nearly 10 times softer than the human tongue. This tenderness assists in keeping the saliva thick, as the insect gets drawn back to the mouth of the frog.
Frog Saliva Is A 'Sheer-Thinning' Fluid
The study was conducted by Alexis Noel, lead author of the study and postdoctoral fellow in Georgia Institute of Technology and his colleagues.
The research reveals the astonishing fact that frog saliva can change viscosity within moments, enabling the creature to successfully reel in insects in its mouth, without any body movement.
"For frogs, saliva seeps easily when it hits the insect, then thickens up during retraction. It's really an incredible process," explained Noel.
The researchers stated that the change in the viscosity takes place due to shearing forces on the saliva. Thus, the saliva can be called a non-Newtonian fluid.
When the frog whips out its tongue at a high speed to catch its food, the shearing force thins the saliva to a large extent, making it possible to fill the crevices of the insect. While withdrawing the tongue back in its mouth, the saliva thickens up and becomes more viscous than honey.
Scientists were able to identify the accurate shear rate, when the viscosity descends after analyzing the saliva samples of at least 18 frogs. The samples were analyzed by a device known as the rheometer, which is an extremely sensitive device for evaluating fluid properties.
The thickness in frog saliva arises due to the presence of long-chain proteins giving it a more mucus-like consistency when compared to humans.
Noel also states that all the credit cannot be given to the saliva alone as the tongue plays a major role by acting like a bungee cord. The frog's tongue while pulling itself back stretches and deforms to keep the bug in contact.
Practical Applications Of Frog Saliva
The researchers suggest that the frog saliva could someday even help in designing an adhesive which is soft and would be able to work at high speeds.
"Maybe even on a conveyor belt in a manufacturing plant, if you had to pick up very delicate components very quickly," said Noel.
The authors received assistance from The Amphibian Foundation, a group working together to bring top researchers studying amphibian biology and conservation to find out the reasons behind their global decline.
The study was published in the Journal of the Royal Society Interface on Feb. 1.
To see how a frog tongue works, watch the video below and let us know what you think in the comments below.
Photo: Jo Garbutt | Flickr