Scientists Record Sticky Frog Tongue in Action Using High-Speed Video Camera

Posted on November 2, 2015

Frog tongue fibers and musculature diagram

Researchers from Kiel University in Germany used high-speed cameras to record frog tongues in action. The horned frog Ceratophrys sp. was recorded catching a cricket with its sticky tongue. Video was also recorded of the frog's tongue hitting a glass slide that was placed in front of a cricket.

The scientists Thomas Kleinteich and Stanislav N. Gorb report in a research paper published in the Royal Society Open Science journal that the frog tongue acts as a muscle-powered adhesive tape. The researchers say, "We found that the tongue rolls over the target during attachment. However, during the pulling phase, the tongue retractor muscle acts perpendicular to the target surface and thus prevents peeling during tongue retraction."

Here is video footage of the frog catching a cricket. It is slowed down 42 times. The video was filmed at 1,000 frames per second and replayed at 24 frames per second.



This second video shows the frog tongue hitting a glass slide that was placed in front of a cricket the frog wanted to eat. It was filmed at 2,000 frames per second and replayed at 12 frames per second (slowed by factor of 167). Take a look:



The researchers say the arrangement of muscle fibers on the frog tongue are spread evenly over the tongue and insert perpendicular to the tongue surface. The researchers say this arrangement of muscle causes an equal force distribution over the contact area and thus allows for high pulling forces. The presence of filiform papillae and a layer of fibrous material underneath the tongue epithelium allows the tongue to adapt to variable surfaces. The entire system is submerged in mucus and fibrils of mucus can still maintain contact with the prey surface even if detachment occurs. This allows for continued pulling forces even if they prey manages to partially escape.

Image: Thomas Kleinteich and Stanislav N. Gorb et.al./ Royal Society