The movement of animals in trees. In every habitat in which trees are present, animals have evolved to move in them. Some animals may only scale trees occasionally, while others are exclusively arboreal. These habitats pose numerous mechanical challenges to animals moving through them, leading to a variety of anatomical, behavioural and ecological consequences including the evolution of sharper claws and prehensile tails.. Furthermore, many of these same principles may be applied to climbing without trees, such as on rock piles or mountains.