Arboreal locomotion small branches, as they may wrap too far around and prick the animal's own paw. Adhesion is an alternative to claws, which works best on smooth surfaces. Wet adhesion is common in tree frogs and arboreal salamanders, and functions either by suction or by capillary adhesion. Dry adhesion is best typified by the specialized toes of geckos, which use van der Waals forces to adhere to many substrates, even glass. Frictional gripping is used by primates, relying upon hairless fingertips. Squeezing the branch between the fingertips generates a frictional force that holds the animal's hand to the branch. However, this
Vicente Pérez Rosales National Park reeds. A diversity of animals of the rodent group live in the park. The larger ones are coipo, coypu, "Myocastor coypus", a webbed-feet animal that inhabits reedy lake and river banks; and Wolffsohn's viscacha, "Lagidium wolffsohni", of the family Chinchillidae, whose preferred habitat is above the timber line. Among the smaller rodents, scientists have shown particular interest for Chilean climbing mouse, "Irenomys tarsalis", and for the long-clawed mole mouse, "Geoxus valdivianus". The park is home to two species of marsupial mammals. Monito del monte, "Dromiciops gliroides", has a semi-arboreal habit. It has been discussed why this South American marsupial appears