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Bats respond to very weak magnetic fields.

Tian LX, Pan YX, Metzner W, Zhang JS, Zhang BF - PLoS ONE (2015)

Bottom Line: We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north.As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north.Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength.

View Article: PubMed Central - PubMed

Affiliation: Biogeomagnetism Group, PGL, Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China; France-China Bio-Mineralization and Nano-Structures Laboratory, Chinese Academy of Sciences, Beijing, China.

ABSTRACT
How animals, including mammals, can respond to and utilize the direction and intensity of the Earth's magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae) can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths occurred during geomagnetic excursions or polarity reversals and thus may have played an important role in the evolution of a magnetic sense. We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north. As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north. When the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT), despite the fact that the artificial field orientation was opposite to the natural geomagnetic field (P<0.05). Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength. This high sensitivity to magnetic fields may explain how magnetic orientation could have evolved in bats even as the Earth's magnetic field strength varied and the polarity reversed tens of times over the past fifty million years.

No MeSH data available.


Related in: MedlinePlus

Angular histograms of roosting locations in the natural geomagnetic field (A) and a polarity reversed magnetic field (B).Field intensity is 51μT. Black arrows indicate the direction and magnitude of the mean resultant vector. Nm: magnetic north.
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pone.0123205.g001: Angular histograms of roosting locations in the natural geomagnetic field (A) and a polarity reversed magnetic field (B).Field intensity is 51μT. Black arrows indicate the direction and magnitude of the mean resultant vector. Nm: magnetic north.

Mentions: Fig 1 shows that N. pancyi in a magnetic field with natural strength preferred to roost near the magnetic north (0°). The mean direction in the natural geomagnetic field was 25°. When the polarity was reversed, the bats changed their roosting preference to the geographic south (162°), i.e. they remained at the (now new, artificial) magnetic north. The mean direction of the bats in both the natural geomagnetic field and the polarity-reversed field were significantly different from a random distribution and from each other (p<0.05) (Table 1).


Bats respond to very weak magnetic fields.

Tian LX, Pan YX, Metzner W, Zhang JS, Zhang BF - PLoS ONE (2015)

Angular histograms of roosting locations in the natural geomagnetic field (A) and a polarity reversed magnetic field (B).Field intensity is 51μT. Black arrows indicate the direction and magnitude of the mean resultant vector. Nm: magnetic north.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414586&req=5

pone.0123205.g001: Angular histograms of roosting locations in the natural geomagnetic field (A) and a polarity reversed magnetic field (B).Field intensity is 51μT. Black arrows indicate the direction and magnitude of the mean resultant vector. Nm: magnetic north.
Mentions: Fig 1 shows that N. pancyi in a magnetic field with natural strength preferred to roost near the magnetic north (0°). The mean direction in the natural geomagnetic field was 25°. When the polarity was reversed, the bats changed their roosting preference to the geographic south (162°), i.e. they remained at the (now new, artificial) magnetic north. The mean direction of the bats in both the natural geomagnetic field and the polarity-reversed field were significantly different from a random distribution and from each other (p<0.05) (Table 1).

Bottom Line: We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north.As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north.Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength.

View Article: PubMed Central - PubMed

Affiliation: Biogeomagnetism Group, PGL, Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China; France-China Bio-Mineralization and Nano-Structures Laboratory, Chinese Academy of Sciences, Beijing, China.

ABSTRACT
How animals, including mammals, can respond to and utilize the direction and intensity of the Earth's magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae) can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths occurred during geomagnetic excursions or polarity reversals and thus may have played an important role in the evolution of a magnetic sense. We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north. As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north. When the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT), despite the fact that the artificial field orientation was opposite to the natural geomagnetic field (P<0.05). Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength. This high sensitivity to magnetic fields may explain how magnetic orientation could have evolved in bats even as the Earth's magnetic field strength varied and the polarity reversed tens of times over the past fifty million years.

No MeSH data available.


Related in: MedlinePlus