Quick and nimble, tree squirrels are able to make their seemingly gravity-defying movements through the trees primarily because of the structure of their feet and ankles. Flexible and rotatable, the joints of their ankles can instantaneously adjust to most any surface, while their slender toes with sharp, pointed claws enable them to hold on. Thus, squirrels can easily accomplish feats, such as descending trees headfirst, at an astonishing pace with very little effort. Such capabilities are invaluable in times of emergency, especially when a hasty retreat from predators is necessary.