Architecture Avoids Flooding, Creates Microclimates

Biological Strategy

Ants

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Image: Alex Wild /

Protect From Excess Liquids

While water is essential to life, too much water or other liquids can overwhelm living systems. Excess liquids can, for example, decrease a living system’s access to oxygen, promote excessive bacterial or fungal growth, or strip away soil and nutrients. To prevent the accumulation of excess liquids, living systems must control the movement of liquids across their boundaries or surfaces. They do so using waterproofing materials or structures, slowing flow, and/or facilitating flow to move the liquid away. Plant leaves, for example, commonly have waxy surfaces comprised of water-repelling chemicals to keep water from engorging the leaves or facilitating bacterial and fungal growth.

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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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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The nests of fungus-growing ants avoid flood damage and create uniform microclimates via necklace-like or tree-like architecture.

Introduction

Leafcutter ants are among the most sophisticated non-human farmers on Earth. They grow crops of a special kind of fungus, which they then eat. The ants “plant” their gardens by spreading bits of leaf around the garden area. The bits of leaf are inoculated with a special kind of bacteria that the ants cultivate. The bacteria convert the leaf bits into a food that the fungus can eat. The fungus then produces a food that the ants can eat.

Image: S. C. Cappellari / Journal of Insect Science /

Image: Alex Wild /

Mycocepurus fungus-growing ants attach their fungal gardens from the ceiling of their nest chambers, and the gardens hang down like curtains.

Image: Alex Wild / http://www.myrmecos.net/ /

Workers of the tiny fungus-growing ant Mycocepurus can be recognized by the crown of spines on the thorax.

The Strategy

The ants build their nests underground, with a system of chambers and tunnels. The gardens are suspended from the ceilings of the chambers, and the ants tend them by continually adding bits of leaf.

Two different species studied both built nests with two different general floor plans: “tree-like” or “necklace-like.”

In tree-like forms, a vertical central shaft reached out with long branches, each ending in a mall room.

In the necklace-like nests, the vertical central shaft is interrupted by chambers, directly leading in and out of each one.

The flow of heat, gases, and moisture throughout the nests creates different microclimates which are useful for managing the growth of the “farming plots” in each chamber.

The Potential

The leafcutter ants’ ability to cultivate a crop of food-producing fungus could be emulated at many different scales. For example, the same principles could be used to cultivate mushrooms or other fungi for food. Alternatively, the ants’ method of using bacteria to convert leaves into a food that the fungus can eat could be used to convert other kinds of organic waste into a food source.

Last Updated August 18, 2016

References

“Both species built their nests in two different ways. The first type possessed a ‘tree-like’ architecture, in which a vertical tunnel led downwards and lateral tunnels branched off at 90° angles from the main tunnel, with a chamber at the end of each side branch. Alternatively, other nests displayed a ‘necklace-like’ architecture, where the main tunnel also led down vertically, but entered each chamber from the top and exited it at the bottom, resulting in an architecture where chambers appeared like pearls on a necklace…Fungus gardens were suspended from the ceiling of the subterranean chambers and originated as small mycelial tufts. Through continual addition of organic debris, the tufts first grew vertically to strands before they expanded laterally until most of the chamber volume was filled with fungus garden curtains.” (Rabeling et al. 2007:1)

Journal article

Comparative Study of Nest Architecture and Colony Structure of the Fungus-Growing Ants, Mycocepurus goeldii and M. smithii

Journal of Insect Science | 13/06/2009 | C. Rabeling, M. Verhaagh, W. Engels

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