Animals living on the tree trunks are known as Arboreal. Arboreal animals are those that live in trees or spend most of their time in trees. These animals have evolved physical adaptations that allow them to move easily among branches and trunks, such as grasping hands and feet, strong limbs, and sharp claws.

Adaptations of Arboreal Animals:
1. Grasping Hands and Feet: Arboreal animals have developed grasping hands and feet that allow them to easily grip onto tree trunks and branches. This adaptation is particularly evident in primates, such as monkeys and apes, which have opposable thumbs that help them grasp objects and climb trees.

2. Strong Limbs: Arboreal animals have strong limbs that are capable of supporting their body weight as they move through the trees. This adaptation is also evident in primates, which have strong arms and legs that allow them to jump from branch to branch.

3. Sharp Claws: Many arboreal animals, such as squirrels and birds, have sharp claws that enable them to grip onto tree trunks and branches as they move through the trees.

Examples of Arboreal Animals:
1. Monkeys and Apes: Monkeys and apes are perhaps the most well-known arboreal animals. They have evolved numerous adaptations that allow them to move through the trees with ease, such as grasping hands and feet and strong limbs.

2. Sloths: Sloths are another example of arboreal animals. They spend most of their lives hanging upside down from tree branches, using their strong limbs and sharp claws to hold on.

3. Tree Frogs: Tree frogs are a type of amphibian that are adapted to life in the trees. They have sticky pads on their toes that allow them to easily grip onto tree trunks and branches.

In conclusion, animals living on the tree trunks are known as Arboreal. These animals have evolved numerous adaptations that allow them to move through the trees with ease, such as grasping hands and feet, strong limbs, and sharp claws.