Scanning electron micrographs of toe pad epithelia in different frog species.

<p>(A) the tree frog <i>R. pardalis</i>, (B) the torrent frog <i>S. guttatus</i> near the edge of pad, and (C) the torrent frog, <i>Odorrana hosii</i>. White solid lines illustrate shortest routes to the edge of pad. White dashed lines are routes across the pad. Arrows show examples of the pointed ends of the epithelial cells of <i>O. hosii</i>. Scale bars: 20 μm.</p

Masses and lengths of the two species used in the experiments.

<p>Masses and lengths of the two species used in the experiments.</p

Attachment performance of male tree frogs (<i>R. pardalis</i>) and male and female torrent frogs (<i>S. guttatus</i>) on the 1125 mm rough surface at a high flow rate.

<p>Male data are from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073810#pone-0073810-g003" target="_blank">Figure 3</a>. Angles of fall for female torrent frogs are significantly higher than those of male tree frogs (Mann-Whitney U-test, ), but lower than those of male torrent frogs (Mann Whitney U-test, ).</p

Contact areas of the two frog species at 5 tilting positions.

<p>Using a special illumination technique (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073810#s2" target="_blank">Materials and Methods</a>), the contact area of ventral body parts (toe pads, belly, thighs and uncategorised areas) of (A) the tree frog (<i>R. pardalis</i>) and (B) the torrent frog (<i>S. guttatus</i>) was measured at 0°, 45°, 90°, 135° and 180°. The photos at the top are images of the frogs at horizontal (0°) and inverted (180°) tilting positions. The plots represent medians of 42 trials from 6 frogs (tree frogs) and 33 trials from 6 frogs (torrent frogs), the percentages at the top representing the proportion of frogs still attached at each tilt angle.).</p

Frog species used in this study.

<p>Males of the (A) Harlequin Tree Frog (<i>R. pardalis</i>) and (B) the Black-spotted Rock Frog (<i>S. guttatus</i>) in their natural habitats.</p

Friction and Adhesion forces per area of different body parts.

<p>Statistical differences are denoted as follows: ‘*’ , ‘**’: , ‘n.s.’: not significant.</p

Scanning electron micrographs of ventral body skin.

<p>Belly (A,B) and ventral thigh epithelium (C,D) of the tree frog (<i>R. pardalis</i>, left column) and the torrent frog (<i>S. guttatus</i>, right column). Insets show structures at higher magnification.</p

Attachment performance of the two frog species under varying conditions.

<p>Comparison of (A) slip angles and (B) fall angles between the tree frog (<i>Rhacophorus pardalis</i>) and the torrent frog (<i>Staurois guttatus</i>) on different wet (‘low’& ‘high’flow rate) and rough surfaces. The details of the statistical tests between the two frog species are listed in Tables S4 and S6 in Supplementary Materials. Intraspecific differences of frog performance on both different surfaces and under different flow regimes are listed in Tables S1 to S3 and S5 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073810#pone.0073810.s002" target="_blank">Supplementary Materials S1</a>.</p

Diagram of the key elements of the tilting platform.

<p>Not drawn to scale.</p