Genevieve is dwarfed by the mound constructed by the Spinifex termite.
Photo: Chris Johnson
September 21, 2001
Cathedrals of the Outback
In other countries, the great grazers of the savannahs are the giraffe, bison, wildebeest and other large herbivores. In northern Australia, the mighty munchers are termites.
Unseen and unheard, these tiny creatures are one of the powerful forces that shape the bushland. Millions of them relentlessly go about their work, harvesting and eating grasses, leaf litter, wood and soil that they persistently chew, and from which they construct their nests.
The nest size, shape and location of the 300 odd species that inhabit Australia, vary significantly. Some are found in trees, below ground or even in your house, while others build ground mounds varying in height from a few centimetres to several meters in the case of the Spinifex termite. The cathedrals constructed by the Spinifex termites are among the largest built anywhere in the world. Their enormous column structures named Gun-boi by aboriginal inhabitants can exceed 7 meters in height and can be more than 50 years old.
Termite mounds throughout the Northern Territory attract great interest from visitors.
It is a bizarre sight to pass by a large expanse of looming red towers, evenly dispersed below a dazzling blue sky. Incredibly they are all orientated north to south. Originally it was believed that these insects could detect the earth's magnetism, but the reason is more likely temperature regulation. In this heat, it is imperative the colony avoids the fierce outback sun shining on the wider side and overheating the nest.
The elaborate construction of the mounds is the work of more than a million insect engineers. As with most social insects that live in colonies, its survival is more important than that of any individual except the queen. The queen is the apex on which the colony depends. The rest of the termites have several forms called castes, and each caste has a separate function in the colony. The workers are the largest termite caste. They gather food for the others, care for the eggs and young and help with the continuous building of the nest. Pale, wingless and eyeless, they have small jaws for chewing the fibrous building materials. The soldiers protect the nest, while the winged productives fly from the parent colony to establish a new one.
Several areas of the outback bushland are strewn with these incredible mounds that can easily dwarf a person, but what is even more remarkable is their interior design. Termites air-condition their homes by opening and closing ventilation channels on the outer surface of the mound, this keeps the temperature constant and prevents overheating, while the high humidity in the nest allows the termites to cultivate fungus as a source of protein. The thick outer walls protect the inner region, where the social life of the colony takes place amongst a honeycomb of chambers and passages. The royal chamber housing the all-important queen is located deep in the heart of the nest. The queen is capable of laying 500 eggs a day once she has reached five years of age, a necessity if she is to relace members of her colony who are consumed daily by hungry kookaburras, monitors, echidnas and numbats.
This is Genevieve Johnson speaking to you from Darwin, Australia.
Log by Genevieve Johnson