Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Orientation of Desert Ants: Every Cue Counts

09.03.2012
Foraging desert ants always find their way back to the nest, even when it is only marked by a magnetic cue, vibration, or carbon dioxide

Desert ants have adapted to a life in a barren environment which only provides very few landmarks for orientation. Apart from visual cues and odors the ants use the polarized sunlight as a compass and count their steps in order to return safely to their home after searching for food.


Cataglyphis noda ants approaching their nest entrance − a small hole in the ground of an experimental tube. Max Planck Institute for Chemical Ecology/Badeke

In experiments with ants of the genus Cataglyphis in their natural habitats in Tunisia and Turkey, behavioral scientists of the Max Planck Institute for Chemical Ecology in Jena, Germany, have now discovered that ants can also use magnetic and vibrational landmarks in order to find their way back to their nest − a small hole in the desert ground.

In addition, carbon dioxide produced by their nestmates’ breathing also helps homing ants to pinpoint their nest entrance. Hence, the ants’ navigational skills prove enormously adaptable to their inhospitable environment.

Returning to the wrong nest can be lethal
Path integration is a fascinating mechanism that ants use for orientation. It combines counting the steps after leaving the nest with determining the direction by using polarized sunlight. This method, which helps the insects to return to their nest, is an important survival formula in the barren environments of deserts. However, the path integrator is error-prone. Therefore ants also use landmarks in order to find home quickly and unerringly: Visual as well as olfactory landmarks serve as important cues. For ants, it is a question of life and death to find the right nest because they may be killed or at least attacked by resident ants if they enter the wrong nest accidentally.

Vibration or magnetism

It is known from leaf-cutting ants that they use vibrational signals for communication. That ants − like birds − also sense the earth’s magnetic field, becomes more and more likely. Therefore, the researchers in Markus Knaden’s lab, behavioral scientists in the Department of Bill Hansson at the Max Planck Institute for Chemical Ecology, wanted to find out whether desert ants − adapted to landscapes providing a minimum of cues − are able to use magnetism and vibrational signals in the absence of other landmarks. “We were very surprised that this is actually the case,” says PhD student Cornelia Buehlmann, who performed the experiments. Trained ants of the species Cataglyphis noda pinpointed their nest without any problem if a battery-powered vibrational device was buried next to the nest entrance so that the ants could localize their nest by using the vibrational landmark. To exclude electromagnetic effects of the device, experiments were performed using the vibrational device without contact to the ground. The result: The ants behaved like their untrained conspecifics. They wandered around aimlessly. If two strong neodym magnets generating a magnetic field of about 21 millitesla (the earth’s magnetic field was, for comparison, only 0.041 millitesla) were placed above ground next to the nest, trained ants again found their home without any problems.

The experiments demonstrated the desert ants’ highly sensitive reaction to vibrational signals. However, it is unknown which sense is involved in the orientation using the artificial magnetic field around the nest. “This doesn’t mean that ants have a kind of sensory organ for the detection of magnetic fields. Their behavior could also be caused by abnormal neural electrical signals due to the strong magnetic field which were memorized by the ants,” says Knaden. Anyhow, neither vibrations nor strong magnetic fields are likely present in the natural vicinity of nest entrances. Therefore it is really astonishing that ants “remember” vibrations or a changing magnetic field as nest landmarks. Ants which have adapted to extremely inhospitable habitats seem to be remarkably flexible in terms of using all senses for navigation.

CO2 as an olfactory landmark

Carbon dioxide produced by the ants’ breathing is an olfactory signal that is constantly present at the nest entrances. That desert ants of the species Cataglyphis fortis use the CO2 plume in order to return to their home could now be shown by experiments performed in Tunisia. The ants ran upwind along the nest plume when the CO2 concentration was not too high and corresponded with the typical plume concentration in the nest vicinity. However, CO2 is released by all the nests and therefore all nests smell the same. Therefore the question is: How can ants recognize their own nest when all smell like home? “We could show in a series of experiments that ants primarily rely on path integration,” explains Cornelia Buehlmann. If ants were released in the close vicinity of their own nest by hand after they had walked to a feeding place, they avoided following the original nest plume of their own nest: The olfactory signal and the number of footsteps did not coincide. In order not to lose their lives in a foreign nest, ants trust path integration more than the chemical signal CO2. They only follow the nest plume when path integration tells them that they are close to home. [JWK/AO]

Original Publications:

Cornelia Buehlmann, Bill S. Hansson, Markus Knaden: Desert ants learn vibration and magnetic landmarks. PLoS ONE 7(3): e33117. DOI:10.1371/journal.pone.0033117

Cornelia Buehlmann, Bill S. Hansson, Markus Knaden: Path integration controls nest-plume following in desert ants. Current Biology, Online First, March 8, 2012; DOI: 10.1016/j.cub.2012.02.029

Further Reading:

Steck, Kathrin: Just follow your nose: homing by olfactory cues in ants. Current Opinion in Neurobiology (2011), DOI:10.1016/j.conb.2011.10.011

Further Information:

Dr. Markus Knaden, +49 3641 57 1421, mknaden@ice.mpg.de
Picture Material:

Angela Overmeyer M.A., Tel. 03641 - 57 2110, overmeyer@ice.mpg.de
or Download via www.ice.mpg.de/ext/735.html

Dr. Jan-Wolfhard Kellmann | Max-Planck-Institut
Further information:
http://www.ice.mpg.de/ext/735.html

More articles from Life Sciences:

nachricht What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Speed data for the brain’s navigation system

06.12.2016 | Health and Medicine

What happens in the cell nucleus after fertilization

06.12.2016 | Life Sciences

IHP presents the fastest silicon-based transistor in the world

05.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>