Nest openings protect from floods: ants

Entrances to ant nests protect them from flooding during high tide by collapsing to block the opening.

Biomimicry Taxonomy

	Maintain physical integrity >
	Protect from abiotic factors >
	Excess liquids

Biomimetic Application Ideas

Preventing flood waters from entering some types of structures.

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[Collapse all sections] Summary

"In Australia, Polyrachis sokolova is found only on the lower shore, in the Ceriops and Rhizophora zones. Uniquely, it nests actually in the mangrove mud. Because of the position of the nests, they are inundated in up to 61 per cent of high tides, for periods of up to 3 1/2 hours. Individual P. sokolova forage at low tide, returning to the nest before the entrances are covered by the tide…The structure of the nests has been studied by making casts with polyurethane foam. They may be up to 45 cm deep in the mud, and have two entrance holes. When the advancing tide reaches the nest, loose soil collapses into the entrances, blocking them and preventing water from penetrating the passages beneath. In this way ants--provided they get back to the nest in time--survive high tide in air trapped in the galleries (Clay and Andersen 1996; Nielsen 1997)." (Hogarth 1999:58-59)

"The nest sites of the mud-nesting ant Polyrhachis sokolova were studied in Darwin Harbour mangroves. They were found from the Ceriops tagal zone to the Rhizophora stylosa zone at elevations ranging from 7.22 to 5.99 meters above the lowest astronomical tide (LAT), which means that the nests were inundated in 13-61% of all high tides and for durations of up to 3.5 hours. The nest structure was studied by excavating nests and making a cast of the galleries using polyurethane foam. The nests were quite extensive, normally with two elevated nest entrances and galleries down to depths of 45 cm. The loose soil particles at the nest entrances collapsed when the tide reached them and formed a stopper which prevented water from intruding into the nest. In this way, the galleries remained dry during high tide. The ants showed a clear swimming or "walking on the surface" behaviour when they returned to the nest just before the entrance collapsed and during ebb. The tolerance of the ants to submergence was tested in the laboratory, with 50% mortality after 11 hours submergence in seawater at 23^o C, and only 3.5 hours in water at 33^o C. Therefore, the nesting behaviour with trapped air in the galleries is necessary for survival in these environments." (Nielsen 1997:15)

About the inspiring organism

Polyrhachis sokolova
Polyrhachis sokolova Forel, 1902

IUCN Red List Status: Unknown

Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Bioinspired products and application ideas

Application Ideas: Preventing flood waters from entering some types of structures.

Industrial Sector(s) interested in this strategy: Construction

Experts

Centre for Tropical Ecosystems Research (cenTER Aarhus)

University of Aarhus

References

Hogarth, P. J. The biology of mangroves. Oxford University Press. 228 p.

Nielsen MG. 1997. Nesting biology of the mangrove mud-nesting ant Polyrhachis sokolova Forel (Hymenoptera, Formicidae) in northern Australia. Insectes Sociaux. 44(1): 15-21.

Nest openings protect from floods: ants

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