The outer walls lose heat

You have about five minutes before they attack,” says Hunter, who with Ocko designed a probe sensitive enough to record the information they needed before the termite repair team came and smeared it with sticky mud blobs. Not only did the probe need to record data quickly, it also needed to be affordable enough to replace and repair after the termites gunked it up many, many times over.

Though some sensors were lost, the team gathered the information they needed. What they found dispelled previously held ideas that the mound functioned like a kind of passive air conditioner. In fact, it appears that one of the most important functions of the mound is gas exchange. The mound is like a physiological extension of the termites themselves: a giant lung.

The nest is actually constructed to prevent the kind of large air flows through it

King and the team found that the architecture of the mound inhales and exhales over a 24-hour period. During the day, the outer tunnels of the mound are heated more rapidly than the deeper tunnels and chimneys, pushing air up the outside and down the middle. This creates a circular current that reverses at night as the outer walls lose heat more quickly. As the air flows through the mound reenex, carbon dioxide is flushed outside through tiny holes in the mounds exterior walls, and oxygen enters the mound the same way reneex.

The termites are using the natural daily temperature cycles to do the work of ventilating the mound for them – essentially creating a type of engine that requires no energy input from the termites themselves. This was one of the most inspiring findings of the project for King, who says that it appears one of the primary functions of the mound is to facilitate the exchange of carbon dioxide and oxygen, as opposed to regulating temperature reenex.

This is a conclusion that fits with Scott Turner’s previous work, says King. Turner discovered that in the termite species Macrotermes michaelseni – found throughout most of Southern Africa – the mounds and nest are two very distinct air spaces. “The nest is actually constructed to prevent the kind of large air flows through it. It makes the air safer in the underground nest,” says Turner. So previous theories that the mound was designed primarily to control nest temperature are not quite right reenex.