Vast arrays of termite mounds, covering an area the size of Great Britain, were recently discovered in northeastern Brazil.
The regularly spaced and still-inhabited mounds are also visible from space, researchers said in a report published in Current Biology on Nov. 19.
The mounds aren’t nests but the result of the termites’ excavations of a network of interconnected underground tunnels over thousands of years.
The tunneling has left huge quantities of soil deposited in approximately 200 million cone-shaped mounds that cover some 93,626 square miles (243,610 square kilometers).
“These mounds were formed by a single termite species that excavated a massive network of tunnels to allow them to access dead leaves to eat safely and directly from the forest floor. The amount of soil … represents one of the biggest structures built by a single insect species,” said Stephen Martin of the University of Salford in the United Kingdom in a statement.
“This is apparently the world’s most extensive bioengineering effort by a single insect species,” added Roy Funch of Universidade Estadual de Feira de Santana in Brazil. “Perhaps most exciting of all—the mounds are extremely old—up to 4,000 years, similar to the ages of the pyramids.”
On the ground, the mounds are largely hidden from view by forests in northeastern Brazil. They were discovered by scientists in recent decades when some of the forest area was cleared for pasture.
Soil samples indicated that the mounts were created 690 to 3,820 years ago.
The researchers said the strangely regular spatial pattern of the mounds was not driven by competition but that the mound pattern arose through self-organization, positing that a pheromone map might allow the termites to take the fastest route to any location in the colony using the tunnels.
“We propose the mound pattern arose through self-organizational processes facilitated by the increased connectivity of the tunnel network, which is driven by the episodic leaf-fall in the caatinga,” the team wrote in the report.
“The spatial distribution of chemicals, such as alkene and alkadiene isomers, could create a pheromone map, allowing the termites to minimize their travel time from any location in the colony to the nearest waste mound. This vast permanent tunnel network allows safe access to a sporadic food supply,” the report continues.
“It’s incredible that, in this day and age, you can find an ‘unknown’ biological wonder of this sheer size and age still existing, with the occupants still present,” Martin said.
Researchers said further study on the mounds is warranted to answer more questions, such as how they’re physically structured since a queen chamber hasn’t been pinpointed.
Along with Martin and Funch, the report was authored by Paul Hanson of the Conservation and Survey Division at the School of Natural Resources at the University of Nebraska-Lincoln and Eun-Hye Yoo of the Department of Geography at the University at Buffalo, the State University of New York.
