Tiny Torrent Frogs Show Superior Grip

Tiny torrent frogs are able to hang on to slippery surfaces better than their tree frog brethren because they use virtually their entire underside to grip surfaces, according to a study published in PLOS One.

Researchers from University of Glasgow and other institutions examined the attachment abilities of the torrent frog (Staurois guttatus) and tree frogs (Rhacophorus pardalis), and found that the former has superior attachment abilities on wet and slippery terrain.

Both frogs preformed equally well on dry, smooth surfaces, but the torrent frog excelled at clinging on to extremely wet, steep and rough surfaces.

To learn why the torrent frogs' grip was superior, the research team used advanced visualization techniques to get an up-close view of the underlying mechanisms.

Both frog species, they found, use their toes, belly and thighs to adhere to surfaces, but the torrent frogs increased the area of belly and thighs they used as the surface became steeper.

Tree frogs, in contrast, often lost their grip as the surface became steeper.

"Torrent frogs adhere to very wet and rough surfaces by attaching not only their specialized toe pads (like many tree frogs do) but also by using their belly and ventral thigh skin," said Thomas Endlein, study author from the University of Glasgow. "In addition, torrent frogs exhibit elongated cells on their toe pads which might help to drain off excess water for close surface attachment."