Mounds Accumulate Calcium Carbonate

close up of a brownish red insect with an enlarged head and small pinchers standing on soil

Biological Strategy

Macrotermes termites

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Capture, Absorb, or Filter Chemical Entities

Living systems often require chemical elements and chemical compounds, including complex sugars, proteins, and odor-making compounds, to perform critical activities. These compounds exist in various states–solid, liquid, and gas–and are ubiquitous in soil, water, and air. This requires that living systems not only have ways to capture, absorb, or filter them, but also ways to differentiate among them, selecting those that are valuable or harmful. For example, mangrove trees live with their roots in salty water and sediments. Various mangrove species have different strategies for removing salt from the water they take in so that their tissues can use the fresh water.

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Store Chemical Entities

Chemical entities include elements such as carbon and metals, and compounds such as nutrients and proteins. Living systems must often store chemical entities–for example, for food or protection–temporarily or for long periods; the latter is synonymous with sequestration. Because chemical entities can react with other chemicals, living systems must store these entities so that they are stable and out of the way (for long-term storage) or readily available when needed (for temporary storage). An example of temporary storage is found in crustaceans such as crabs, which must shed their external skeletons as they grow. But first, a crab must absorb as much calcium carbonate from its shell as possible, storing the compound in its blood until the crab can use it to grow a new exoskeleton.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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Mounds of Macrotermes termites accumulate calcium carbonate.

“The presence of appreciable quantities of calcium carbonate in termite mounds on non-calcareous soil has intrigued pedologists for many years. Milne, for example, found a termite mound with 7% calcium carbonate and estimated that it contained about 2 t of calcium carbonate excluding the hard limestone (53% CaC03) base of the mound. The soil below the base of a termite mound may also be calcareous The soil underneath one termite mound in an area of non-calcareous soil was found to have mean of 1.7% calcium carbonate to a depth of 6 m, or about 20 t of calcium carbonate.” (Watson 1974:74)

“A group of islands of varying size on the floodplain of the Okavango alluvial fan, were studied to establish the processes which lead to the initiation and growth of islands. It was found that islands are initiated by the mound-building activities of the termite Macrotermes michaelseni. These termites import fine grained materials to use as a mortar for the construction of epigeal mounds. Their activities create a topographic feature, raised above the level of seasonal flooding, and also change the physical properties and nutrient status of the mound soil. Shrubs and trees are able to colonize these mounds, which results in increased transpiration. As a result, precipitation of calcite and silica from the shallow ground water occurs preferentially beneath the mounds, resulting in vertical and especially lateral growth, causing island expansion.” (McCarthy et al. 1998:291)

Last Updated September 14, 2016

References

Journal article

Calcium carbonate in termite mounds

Watson, J. P.

Journal article

The role of biota in the initiation and growth of islands on the floodplain of the Okavango alluvial fan, Botswana

McCarthy TS; Ellery WN; Dangerfield JM

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