Question

why do arboreal animals not fall from the trees?

Answer 1

Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose numerous mechanical challenges to animals moving through them and lead to a variety of anatomical, behavioral and ecological consequences as well as variations throughout different species.[1] Furthermore, many of these same principles may be applied to climbing without trees, such as on rock piles or mountains.

The earliest known tetrapod with specializations that adapted it for climbing trees was Suminia, a synapsid of the late Permian, about 260 million years ago.[2]

Some invertebrate animals are exclusively arboreal in habitat, such as the tree snail.

Answer 2

Arboreal animals have special claws which help them climb trees. These claws give them a better grip to prevent from falling. That is why monkeys, koalas and squirrels never fall from trees. Even while sleeping, they grip on to trees.