“See this hole?” Diego asks, pointing to a spot on the trunk of the tree just over his head. “It’s where the ants come and go.”

I had noticed the trees from the first day in Costa Rica. They have flat gray bark and rings up and down their trunks and limbs. But the leaves… What beautiful amazing leaves! I could not resist turning my lens to the leaves.

The locals call them “trumpet” trees. I would call them “umbrella” trees. In a sudden tropical rainstorm, one could do way worse than to take refuge under a Cecropia tree.

I also noticed that the animals seem to love the Cecropia trees. Not only monkeys, but the only 3-toed sloth we saw in the wild was high in a Cecropia tree.

So the Cecropia tree serves the rain forest in general, but what our guide Diego was explaining to me was that the Cecropia tree and Aztec ants have a special, symbiotic relationship. The trunk of the tree is hollow and the ants live inside.

The tree is shelter and glycogen-rich food for the ants. In return, the ants drive off herbivorous insects and keep vines from growing on the trees. The ants chew on a part of the vine until it dies and falls.

These creatures–ant and tree–know they need each other.