Ants Versus Elephants

It is a fairly perfect example of what scientists call symbiosis: A species of acacia tree on the plains of East Africa provides shelter and food to a species of ants. In return, the ants fiercely defend the trees.

They defend them against elephants!

Scientists from the University of Florida recently published the results of their research into this symbiotic relationship—which is merely a scientific way of describing what many of the rest of us informally refer to as cooperation between two species, or, to use a familiar human metaphor, “one hand washing the other.” According to the researchers, when elephants attack the whistling-thorn, or ant plant, acacia trees to strip them of their leaves and other juicy parts, the ants charge out in a biting swarm that heads right for the the most sensitive part of the multi-ton animals’ anatomy: the tender insides of their trunks. These ant attacks are usually successful at driving off the elephants.

In return for serving as the acacia’s armed forces, the trees provide a place for the ants to live, in addition to food in the form of a sweet sap that the tree excretes.

Before coming to their conclusions about the strange three-sided tree-ant-and-elephant relationship, the Florida researchers conducted a number of experiments. First, they needed to make sure the “ant plant” acacias were actually palatable to elephants, who tend to leave them alone in the wild. They did this by feeding ant-plant leaves and other tree parts to captive elephants—who ate them just as eagerly as they ate other species of acacia.

Next, they needed to find out what would happen if they removed the ants from ant plants growing in elephant habitat. Once the ants were gone, the elephants readily attacked and ate the trees the insects had formerly lived in, thereby proving the role of the ants in defending the acacias.

Click here to see more, including a short video by one of the University of Florida scientists who conducted the research.