They may be little, but they build big. Termites are a type of detritus-munching insect that live in vast, social colonies. There are around 3,000 different species, found all over the world.
They build complex, chambered nests to nurture and raise their young. Sometimes these nests are in trees. Sometimes they are in rotting chunks of wood. But sometimes, they are underground, with enormous above-ground chimneys for ventilation.
- The weirdest animal homes: 10 extraordinary shelters by nature's best architects
- Supersized animal homes: From ant megacities and termite towers to giant bird nests we take a tour of nature’s mega mansions
These chimneys are known as termite mounds. Fashioned from just three simple ingredients - soil, saliva and faeces - they are robust structures than can survive for thousands of years. In Australia’s northern territory, the appropriately named cathedral termite (Nasutitermes triodiae) builds some of the tallest mounds.
Their lofty chimneys stand up to 8 metres tall. That’s the equivalent of humans constructing a building the height of four Burj Khalifa towers or 320 Big Bens, all without blueprints, surveyors or building regulations.
Although the monolith-like structures may look basic from the outside, on the inside they are anything but. Termite mounds contain an intricate network of tunnels, engineered to facilitate the flow of clean air into the nest, and the exit of toxic gases. They also help to keep the nest at a cool, consistent temperature. Think of like termite aircon.
As well as building vertically, some termites build horizontally too. When the resources around one mound become depleted, worker termites strike out sideways. They construct lateral tunnels to nearby sites, where they build new nests and mounds. In this way, whole cities of termite mounds can evolve.
The largest of these, known as the caatinga mounds, is in a dry, tropical forest in north-east Brazil. Here, the mounds are conical structures made of excavated earth. Each mound or ‘murundas’ is around 2.5 metres tall and 9 metres in diameter. What is truly staggering, however, is how many there are. Two hundred million mounds exist, spread over an area the size of Great Britain. The collection is so large and so striking, it can even be seen from space.
The termites who built the mounds, in successive generations over several thousands of years, shifted a staggering 10 km3 of earth, equivalent to around 4000 great pyramids of Giza. Each mound contains around 50 cubic metres of soil, but there are no delicate ventilation shafts here.
Instead, a single, central tunnel descends from the top of the mound to the ground, where it intersects with an extensive network of underground tunnels and leaf-laden larders. At night, working parties of up to fifty termites emerge onto the forest floor from a series of small, temporary tunnels that they create specially for the job. Then they grab a leaf or two, drag it back to the colony, and seal the temporary tunnels behind them.
So, termites don’t just make the tallest animal-built structures, they also construct the biggest underground cities. According to the scientists who have studied them, the caatinga mounds are the greatest known example of ecosystem engineering by a single insect species.
