The Green Planet

(insects chirping) -

Narrator

Now the pieces are carried back to the underground fungus. The ants can run at speeds of six feet a minute (feet clicking) and each can carry a load 10 times its own weight. (dramatic music) It's a river of leaves across the jungle floor. Part of a vast network that extends from miles through the forest. To avoid congestion, worker ants dig trenches around obstacles. (dramatic music) Thousands of pieces are delivered every hour to the waiting fungus. (dramatic music) Fed by such a continuous supply, the fungus grows rapidly filling the chambers in which it lives. So the ants excavate more space. It seems that the fungus has the upper hand and the Bixa tree will not survive. (dramatic music) But it fights back, using chemical warfare. The Bixa tree floods its leaves with toxins that could kill the distant fungus. As the ants carry the fragments back, they are themselves poisoning the fungus on the tree's behalf. (dramatic music) It's a long distance attack. As the poison takes effect, the ants sense that their fungus is weakening (dramatic music) and they respond to its signals by changing to another source of leaves. (dramatic music) So the plant's chemical response forces the ants to constantly switch from tree to tree.