The family of tree frogs is one of the most diverse among the class of amphibians. At present, some 800 species of these largely climbing amphibians are known. The animals cling to various surfaces with the undersides of their extremities and moist underbelly by adhesion. As they also have rounded toe and finger pads this makes tree frogs exceptional climbers.
Even absolutely smooth surfaces do not represent a problem. The flexible distal phalanx of the “frog fingers” is pressed against the surface and fixated through slight contraction.
A number of different substructures can be seen on the suction pads under the scanning electron microscope, and their complex interplay gives these small animals amazing grip.
Of course our frog valves cannot climb, but they do adhere firmly and seal reliably once they have been attached to the working channel of an endoscope – and they are green, too.