Narrator: Now listen to part of a lecture in a biology class.
Professor: Ok. Now, a good example of this is leaf-cutter ants. They use this kind of system when they need to get food--leaves to their nest.
What happens is that they're separated into three different groups, and each group has a different part in the process of transporting food back to the nest.
So the first group, their job is to climb up a tree and start cutting off pieces of leaves. But instead of carrying the leaf pieces back down the tree, the ants just let go of the pieces so they fall down to the ground below.
And after a while, all these leaf pieces collect in a pile at the bottom of the tree. Then there's a second group of ants waiting to help.
This second group's job is to cut the leaves down into smaller, more manageable pieces that are easier for them to carry. Then they take these smaller pieces of leaves to a place that's part way back to the nest.
Finally, the last group of ants takes over, and they have the job of actually bringing the leaf pieces back from the trail to the nest.
The system works well since each ant has a specific job to do, the work gets done faster than if they were all working independently.
And since none of the ant has to keep climbing up and down a tree, they can all do their jobs without tiring out too soon.