The East African savannahs support millions of grazers.
Each year they devour millions of tons of grass,
and yet there's one creature here whose impact is far greater than all these animals combined.
They're found wherever grass grows on the planet,
yet their labours go almost entirely unnoticed.
One of the most remarkable is found here on the grasslands of South America.
These blades are so tough that virtually no large grass eaters can stomach them.
Yet they're harvested on an industrial scale... by tiny grass cutter ants.
But they themselves can't digest one bit of it. So, why bother?
The answer is underground, and it's very ingenious.