Stephen J. Martin spotted large mounds—some 10 feet tall and 30 feet wide—along with the roadside as he drove through a remote part of northeast Brazil.
An entomologist at the University of Salford in England who was in Brazil for research on the worldwide decline of honeybees Dr Martin said, “After 20 minutes, we were still driving through these, and I started saying, ‘Well, what are they?’”
At a glance, he thought that they might be piles of dirt dislocated from the construction of the road. Instead, his associates told him, “Oh, they’re just termite mounds.”
And Martin replied, “And I went, ‘You’re really sure about that?’ And they’re like, ‘Well, I don’t know. I think so.’”
On Monday a research article was published in the journal Current Biology wherein Dr Martin, Dr Funch and their colleagues reported their findings.
Scientists estimate around 200 million mounds.
The cone-shape mounds are the opus of Syntermes dirus—the largest termite species that are around half an inch long. Spaced on average about 60 feet apart, these mounds are spread across an area as large as Britain.
Dr Martin said, “As humans, we have never built a city that big, anywhere”.
The scientists were taken aback by the results of the radioactive dating of the 11 mounds. The youngest dated back to 690 years old. The oldest was at least 3,820 years old.
The scientists further estimated that to build 200 million mounds, the termites have dug up around 2.4 cubic miles of dirt—a volume that is equal to 4,000 great pyramids of Giza. The scientists wrote, “This the greatest known example of ecosystem engineering by a single insect species.”
The surprising thing that came out was the fact that the mounds turned out to be mounds only. While the other termites build mounds that are full of complicated networks and provide ventilation for underground nests.
After cutting through some of the mounds, Dr Martin, and Dr Funch found a single central tube leading to the top as they never came across any nests.
These mounds were simply piles of dirt and not ventilation structures. As the termites dug up a network of tunnels below the landscape so they needed somewhere to dispose of the excavated dirt. So, they carried the dirt up the central tube to the top of a mound and cast off.
That might also highlight the reason behind spacing between the mounds. Initially, Dr Martin and Dr Funch considered it as the outcome of rival colonies. But when they relocated a termite from one mound to a neighboring mound, there was no conflict, indicating they were from the same family.
They finally concluded that the pattern was efficient enough to space the garbage piles.