Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Navigating with the sixth sense

27.04.2018

Desert ants use the Earth's magnetic field for orientation, a new study has found which was conducted by scientists of the University of Würzburg. This provides ants the cue to find their way back to the nest.

Desert ants (Cataglyphis) spend the first weeks of their life exclusively in their dark underground nest. For around four weeks, they nurse the queen and the brood, dig tunnels, build chambers or tidy up. At some point, they leave the nest to start their outdoor career, working as foragers until their death.


Desert ants (Cataglyphis) at the nest entrance.

Foto: Pauline Fleischmann


Looking for the nest entrance, Desert Ants use the geomagnetic field for orientation (black). This can be concluded from experiments, in which the geomagnetic field was artificially rotated (red).

Graphic: Current Biology

Pirouettes lead the way

Before an ant sets out to forage, it has to calibrate its navigational system, however. For this purpose, the insects exhibit a rather peculiar behaviour during two to three days: They perform so-called learning walks to explore the vicinity of the nest entrance and frequently turn about their vertical body axes while doing so.

High-speed video recordings show that the ants stop repeatedly during these pirouetting motions. What is special about the longest of these stopping phases is that at this moment the ants always look back precisely to the nest entrance, although they are unable to see the tiny hole in the ground.

Researchers from the Biocenter of the University of Würzburg have now made the surprising discovery that the desert ant uses the Earth's magnetic field as orientation cue during these calibration trips. This ability had been previously unknown for desert ants.

Publication in Current Biology

Pauline Fleischmann and Robin Grob, research assistants of Professor Wolfgang Rössler, who holds the Chair of Zoology II at the Biocentre of the University of Würzburg, conducted the tests in the summer of 2017. The scientists designed the experiment together with Professor Rüdiger Wehner from the Brain Research Institute of the University of Zurich and physicist Valentin Müller from the University of Würzburg. They present their research results in the current issue of the journal Current Biology.

"While they are foraging for food, desert ants venture several hundred metres away from their nest, pursuing a sinusoidal path that includes larger loops. Once they have found food, they return to the nest entrance in a straight line," Wolfgang Rössler describes the ants' astonishing navigational abilities. The researchers had known already that the ants rely on the position of the sun and landmarks as orientational cues and integrate this information with the steps travelled.

Experiments in Greece

Recent research results have shown, however, that the desert ant also looks back to the nest entrance during its learning walks in the absence of solar information or landscape cues. "This sparked the idea that the insects might navigate using the Earth's magnetic field as a cue, as some birds do," Pauline Fleischmann says.

To confirm their hypothesis, the researchers travelled to the south of Greece where Cataglyphis ants are native. They took a 1.5-m-high pair of Helmholtz coils with them. A defined current passed through the coils creates an almost homogeneous, precisely known magnetic field in between the coils. This enabled the researchers to study the behaviour of the desert ants during their learning walks in their natural habitat under controlled conditions.

A surprising outcome

The result was unambiguous: When the scientists changed the orientation of the magnetic field, the desert ants no longer looked towards the real nest entrance but towards a predictable new location – the fictive nest entrance.

"Their path integration provides them with a new vector to the nest based on the information of the magnetic field," Wolfgang Rössler explains. The scientists admit that they had been surprised by this finding. They say that although individual ant species are known to respond to changes in the magnetic field under certain conditions, the necessity and distinct influence on navigation in Cataglyphis ants was unexpected.

With this result the researchers have "opened a new door which raises a lot of further questions." One of them is: "When do desert ants use their magnetic sense?" It might well be that they already rely on it during the first weeks of their life which they spend underground. After all, a navigational aid can be quite useful in total darkness. But this is only a hypothesis at this point.

Interesting for neuroscience, computer science and robotics

The second question the scientists want to tackle is how and whether the ants switch between the different navigational cues - the position of the sun, landmarks and the magnetic field. Experienced foragers are already known to perform re-learning walks when they are forced to do so, for example by changing the environment at the nest entrance. It is unclear, however, whether they rely on magnetic field cues again in this case or whether they use their solar compass as during the foraging trips.

And ultimately, there is of course the overarching question of where the magnetic field sensor is located and how it works. According to Wolfgang Rössler, this question takes you deep into the field of orientational and navigational research in insects.

How does the comparably small ant brain manage to store navigational information on the position of the sun, the magnetic field and landmarks and integrate this information with distance data from their step counter? Rössler believes that this question goes far beyond the field of behavioural research and neurosciences and is of great interest for computer science and robotics, too.

The geomagnetic field is a compass cue in Cataglyphis ant navigation. Pauline Nikola Fleischmann, Robin Grob, Valentin Leander Müller, Rüdiger Wehner, Wolfgang Rössler. Current Biology (2018)

Contact

Prof. Dr. Wolfgang Rössler, Department of Zoology II, T: +49 931 31-84306, roessler@biozentrum.uni-wuerzburg.de

Dr. Pauline Fleischmann, Department of Zoology, T: +49 931 31-80347, pauline.fleischmann@uni-wuerzburg.de

Robin Grob, Department of Zoology, T: +49 931 31-89217, robin.grob@uni-wuerzburg.de

Weitere Informationen:

https://doi.org/10.1016/j.cub.2018.03.043 See the original paper

Gunnar Bartsch | Julius-Maximilians-Universität Würzburg

More articles from Life Sciences:

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

nachricht Pollen taxi for bacteria
18.07.2018 | Technische Universität München

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Machine-learning predicted a superhard and high-energy-density tungsten nitride

18.07.2018 | Materials Sciences

NYSCF researchers develop novel bioengineering technique for personalized bone grafts

18.07.2018 | Life Sciences

Why might reading make myopic?

18.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>