英文

Narrator: Listen to part of a lecture in a biology class.

Professor: In the rain forest, many animals live mainly in the canopy. In the treetops.

This allows these animals to avoid predators that live on the rain forest floor. However, animals can't just stay in one tree all the time.

There wouldn't be enough food there. They have to move in between the trees to find food. But moving between trees, which may be far apart from each other, isn't an easy task for some mammals.

Mammals that can't fly. But some mammals have developed special ways of traveling through the trees without descending to the ground.

So, some mammals have developed special physical features that, allow them to move between trees. While they can't fly, they do have sort of wing like appendages that help them to glide.

They can jump and then stay aloft in the air for a little while long enough to get from one tree to another and, avoid predators on the ground.

For example, there's a small mammal, a type of lemur that has flaps of skin in between its front and back legs, which look kind of like a bird's wings.

When a lemur jumps and stretches out its legs, these flaps of skin catch the air and help carry it to the next tree, but not every mammal that lives in the trees has these special features.

So, some mammals rely on physical force to travel between trees and find food. They take advantage of their own body weight.

To move or bend the trees closer together. So that, they can move from one tree to another.

There's a large species of ape, the orangutan that does this. If an orangutan sees some fruit in a nearby tree that it can't quite reach,

The orangutan wraps itself around the trunk of the tree it's in and starts to sway back and forth. This movement bends the tree over so that the orangutan can just reach to the branch of the other tree and pull itself across.