scholarly journals Eyes are essential for magnetoreception in a mammal

2020 ◽  
Vol 17 (170) ◽  
pp. 20200513
Author(s):  
Kai R. Caspar ◽  
Katrin Moldenhauer ◽  
Regina E. Moritz ◽  
Pavel Němec ◽  
E. Pascal Malkemper ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Surgical Removal ◽  
Magnetic Orientation ◽  
Significant Preference ◽  
Compass Orientation ◽  
Subterranean Rodent ◽  
Orientation Behaviour ◽  
Mole Rat ◽  
Magnetic Compass Orientation ◽  
Magnetic Sense

Several groups of mammals use the Earth's magnetic field for orientation, but their magnetosensory organ remains unknown. The Ansell's mole-rat ( Fukomys anselli , Bathyergidae, Rodentia) is a microphthalmic subterranean rodent with innate magnetic orientation behaviour. Previous studies on this species proposed that its magnetoreceptors are located in the eye. To test this hypothesis, we assessed magnetic orientation in mole-rats after the surgical removal of their eyes compared to untreated controls. Initially, we demonstrate that this enucleation does not lead to changes in routine behaviours, including locomotion, feeding and socializing. We then studied magnetic compass orientation by employing a well-established nest-building assay under four magnetic field alignments. In line with previous studies, control animals exhibited a significant preference to build nests in magnetic southeast. By contrast, enucleated mole-rats built nests in random magnetic orientations, suggesting an impairment of their magnetic sense. The results provide robust support for the hypothesis that mole-rats perceive magnetic fields with their minute eyes, probably relying on magnetite-based receptors in the cornea.

scholarly journals Eyes are essential for magnetoreception in a mammal

2020 ◽  
Author(s):  
Kai R. Caspar ◽  
Katrin Moldenhauer ◽  
Regina E. Moritz ◽  
E. Pascal Malkemper ◽  
Sabine Begall
Keyword(s):  
Magnetic Field ◽  
Magnetic Orientation ◽  
Orientation Behavior ◽  
Significant Preference ◽  
Compass Orientation ◽  
Subterranean Rodent ◽  
Magnetic Parameters ◽  
Mole Rat ◽  
Magnetic Compass Orientation ◽  
Magnetic Sense

AbstractSeveral groups of mammals use the Earth’s magnetic field for orientation, but their magnetosensory organ remains unknown. The Ansell’s mole-rat (Fukomys anselli) is a subterranean rodent with innate magnetic orientation behavior. Previous studies proposed that its magnetoreceptors are located in the eye. To test this hypothesis, we assessed magnetic orientation in enucleated mole-rats.Initially, we demonstrate that enucleation of mole-rats does not lead to changes in routine behaviors. We then studied magnetic compass orientation by employing a well-established nest building assay. To ensure that directional responses were based on magnetic parameters, we tested animals under four magnetic field alignments. In line with previous studies, control animals exhibited a significant preference to build nests in magnetic south-east. In contrast, enucleated mole-rats built nests in random magnetic orientations, suggesting an impairment of their magnetic sense. The results provide robust support for the hypothesis that mole-rats perceive magnetic fields with their minute eyes.

Magnetic compass orientation in the blind mole rat Spalax ehrenbergi

2001 ◽  
Vol 204 (4) ◽  
pp. 751-758 ◽  
Author(s):  
T. Kimchi ◽  
J. Terkel
Keyword(s):  
Magnetic Field ◽  
Magnetic Compass ◽  
Food Store ◽  
Earth’S Magnetic Field ◽  
Compass Orientation ◽  
Spalax Ehrenbergi ◽  
Mole Rat ◽  
Earth's Magnetic Field ◽  
Magnetic Compass Orientation ◽  
Directional Preference

The blind mole rat Spalax ehrenbergi is a solitary, subterranean rodent that digs and inhabits a system of branching tunnels, with no above-ground exits, which it never leaves unless forced to. To survive, the mole rat must be able to orient efficiently in its tunnel system. The sensory channels available for spatial orientation in the subterranean environment are restricted in comparison with those existing above ground. This study examined the possibility that the mole rat is able to perceive and use the earth's magnetic field to orient in space. Experiments were performed using a device constructed from a pair of electromagnetic ‘Helmholtz coils’, which create a magnetic field whose direction and strength can be altered. In the first experiment, we tested a group of mole rats (N=33) in an eight-armed maze under the earth's natural magnetic field to determine whether they have directional preferences for the location of their sleeping nest, food chamber and toilet site. A second group of mole rats (N=30) was tested for their directional preference after the earth's magnetic field had been experimentally shifted by 180 degrees. We found that the first group exhibited a significant preference (P<0.001) to build both their sleeping nest and their food store in the southern sector of the maze, whereas the second group shifted the location of their nests (P<0.01) and food store (P<0.05), to the northern sector of the maze, corresponding to the shift in the magnetic field. In the second experiment, we tested whether the magnetic compass orientation found in the first experiment depends on a light stimulus by testing a group of mole rats in the eight-armed maze under total darkness. No significant difference in directional preference between light and dark test conditions was observed. It can be concluded, therefore, that, in contrast to some amphibians and birds, magnetic compass orientation in the mole rat is independent of light stimulation. In the third experiment, we examined whether mole rats (N=24) use the earth's magnetic field as a compass cue to orient in a labyrinth. In the first stage (trials 1–13), the animals were trained to reach a goal box at the end of a complex labyrinth until all individuals had learned the task. In the second stage (trial 14), half the trained mole rats underwent another labyrinth trial under the earth's natural magnetic field, while the other half were tested under a magnetic field shifted by 180 degrees. We found a significant decrease (P<0.001) in performance of the mole rats tested under the shifted magnetic field compared with the group tested under the natural magnetic field. The findings from these experiments prove that the mole rat is able to perceive and use the earth's magnetic field to orient in space.

scholarly journals Avian magnetic compass can be tuned to anomalously low magnetic intensities

2013 ◽  
Vol 280 (1763) ◽  
pp. 20130853 ◽  
Author(s):  
Michael Winklhofer ◽  
Evelyn Dylda ◽  
Peter Thalau ◽  
Wolfgang Wiltschko ◽  
Roswitha Wiltschko
Keyword(s):  
Magnetic Field ◽  
Exposure Time ◽  
Geomagnetic Field ◽  
Magnetic Compass ◽  
Radical Pair Mechanism ◽  
Compass Orientation ◽  
Directional Information ◽  
Total Exposure Time ◽  
Magnetic Compass Orientation ◽  
Local Intensity

The avian magnetic compass works in a fairly narrow functional window around the intensity of the local geomagnetic field, but adjusts to intensities outside this range when birds experience these new intensities for a certain time. In the past, the geomagnetic field has often been much weaker than at present. To find out whether birds can obtain directional information from a weak magnetic field, we studied spontaneous orientation preferences of migratory robins in a 4 µT field (i.e. a field of less than 10 per cent of the local intensity of 47 µT). Birds can adjust to this low intensity: they turned out to be disoriented under 4 µT after a pre-exposure time of 8 h to 4 µT, but were able to orient in this field after a total exposure time of 17 h. This demonstrates a considerable plasticity of the avian magnetic compass. Orientation in the 4 µT field was not affected by local anaesthesia of the upper beak, but was disrupted by a radiofrequency magnetic field of 1.315 MHz, 480 nT, suggesting that a radical-pair mechanism still provides the directional information in the low magnetic field. This is in agreement with the idea that the avian magnetic compass may have developed already in the Mesozoic in the common ancestor of modern birds.

scholarly journals Changing and shielded magnetic fields suppress c-Fos expression in the navigation circuit: input from the magnetosensory system contributes to the internal representation of space in a subterranean rodent

2010 ◽  
Vol 7 (50) ◽  
pp. 1275-1292 ◽  
Author(s):  
Tomáš Burger ◽  
Marcela Lucová ◽  
Regina E. Moritz ◽  
Helmut H. A. Oelschläger ◽  
Rastislav Druga ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spatial Representation ◽  
Sensory Information ◽  
Internal Representation ◽  
Thalamic Nuclei ◽  
Compass Orientation ◽  
Subterranean Rodent ◽  
Motor Information ◽  
Fos Expression

The neural substrate subserving magnetoreception and magnetic orientation in mammals is largely unknown. Previous experiments have demonstrated that the processing of magnetic sensory information takes place in the superior colliculus. Here, the effects of magnetic field conditions on neuronal activity in the rodent navigation circuit were assessed by quantifying c-Fos expression. Ansell's mole-rats ( Fukomys anselli ), a mammalian model to study the mechanisms of magnetic compass orientation, were subjected to natural, periodically changing, and shielded magnetic fields while exploring an unfamiliar circular arena. In the undisturbed local geomagnetic field, the exploration of the novel environment and/or nesting behaviour induced c-Fos expression throughout the head direction system and the entorhinal–hippocampal spatial representation system. This induction was significantly suppressed by exposure to periodically changing and/or shielded magnetic fields; discrete decreases in c-Fos were seen in the dorsal tegmental nucleus, the anterodorsal and the laterodorsal thalamic nuclei, the postsubiculum, the retrosplenial and entorhinal cortices, and the hippocampus. Moreover, in inactive animals, magnetic field intensity manipulation suppressed c-Fos expression in the CA1 and CA3 fields of the hippocampus and the dorsal subiculum, but induced expression in the polymorph layer of the dentate gyrus. These findings suggest that key constituents of the rodent navigation circuit contain populations of neurons responsive to magnetic stimuli. Thus, magnetic information may be integrated with multimodal sensory and motor information into a common spatial representation of allocentric space within this circuit.

scholarly journals Magnetic Compass Orientation in a Palaearctic–Indian Night Migrant, the Red-Headed Bunting

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1541
Author(s):  
Tushar Tyagi ◽  
Sanjay Kumar Bhardwaj
Keyword(s):  
Magnetic Field ◽  
Northern Hemisphere ◽  
Spring Migration ◽  
Magnetic Compass ◽  
Day Length ◽  
Compass Orientation ◽  
Long Distance ◽  
Specific Direction ◽  
Magnetic Compass Orientation ◽  
Overcast Sky

Red-headed buntings (Emberiza bruniceps) perform long-distance migrations within their southerly overwintering grounds and breeding areas in the northern hemisphere. Long-distance migration demands essential orientation mechanisms. The earth’s magnetic field, celestial cues, and memorization of geographical cues en route provide birds with compass knowledge during migration. Birds were tested during spring migration for orientation under natural clear skies, simulated overcast skies at natural day length and temperature, simulated overcast at 22 °C and 38 °C temperatures, and in the deflected (−120°) magnetic field. Under clear skies, the red-headed buntings were oriented NNW (north–northwest); simulated overcast testing resulted in a northerly mean direction at local temperatures as well as at 22 °C and 38 °C. The buntings reacted strongly in favor of the rotated magnetic field under the simulated overcast sky, demonstrating the use of a magnetic compass for migrating in a specific direction.

scholarly journals Night-migratory garden warblers can orient with their magnetic compass using the left, the right or both eyes

2009 ◽  
Vol 7 (suppl_2) ◽  
Author(s):  
Christine Maira Hein ◽  
Manuela Zapka ◽  
Dominik Heyers ◽  
Sandra Kutzschbauch ◽  
Nils-Lasse Schneider ◽  
...  
Keyword(s):  
Magnetic Compass ◽  
Compass Orientation ◽  
Orientation Behaviour ◽  
Eyes Open ◽  
Magnetic Compass Orientation ◽  
Migratory Songbird ◽  
Sylvia Borin ◽  
The Right

Several studies have suggested that the magnetic compass of birds is located only in the right eye. However, here we show that night-migrating garden warblers ( Sylvia borin ) are able to perform magnetic compass orientation with both eyes open, with only the left eye open and with only the right eye open. We did not observe any clear lateralization of magnetic compass orientation behaviour in this migratory songbird, and, therefore, it seems that the suggested all-or-none lateralization of magnetic compass orientation towards the right eye only cannot be generalized to all birds, and that the answer to the question of whether magnetic compass orientation in birds is lateralized is probably not as simple as suggested previously.

scholarly journals The geomagnetic environment in which sea turtle eggs incubate affects subsequent magnetic navigation behaviour of hatchlings

2014 ◽  
Vol 281 (1791) ◽  
pp. 20141218 ◽  
Author(s):  
Matthew J. Fuxjager ◽  
Kyla R. Davidoff ◽  
Lisa A. Mangiamele ◽  
Kenneth J. Lohmann
Keyword(s):  
Magnetic Field ◽  
Sea Turtle ◽  
Northern Coast ◽  
Magnetic Orientation ◽  
Loggerhead Sea Turtle ◽  
Orientation Behaviour ◽  
Migratory Route ◽  
First Time ◽  
Northeastern Atlantic

Loggerhead sea turtle hatchlings ( Caretta caretta ) use regional magnetic fields as open-ocean navigational markers during trans-oceanic migrations. Little is known, however, about the ontogeny of this behaviour. As a first step towards investigating whether the magnetic environment in which hatchlings develop affects subsequent magnetic orientation behaviour, eggs deposited by nesting female loggerheads were permitted to develop in situ either in the natural ambient magnetic field or in a magnetic field distorted by magnets placed around the nest. In orientation experiments, hatchlings that developed in the normal ambient field oriented approximately south when exposed to a field that exists near the northern coast of Portugal, a direction consistent with their migratory route in the northeastern Atlantic. By contrast, hatchlings that developed in a distorted magnetic field had orientation indistinguishable from random when tested in the same north Portugal field. No differences existed between the two groups in orientation assays involving responses to orbital movements of waves or sea-finding, neither of which involves magnetic field perception. These findings, to our knowledge, demonstrate for the first time that the magnetic environment present during early development can influence the magnetic orientation behaviour of a neonatal migratory animal.

scholarly journals Polarized light modulates light-dependent magnetic compass orientation in birds

2016 ◽  
Vol 113 (6) ◽  
pp. 1654-1659 ◽  
Author(s):  
Rachel Muheim ◽  
Sissel Sjöberg ◽  
Atticus Pinzon-Rodriguez
Keyword(s):  
Magnetic Field ◽  
Radical Pair ◽  
Polarized Light ◽  
Magnetic Compass ◽  
Radical Pair Mechanism ◽  
Magnetic Field Effects ◽  
Compass Orientation ◽  
Magnetic Compass Orientation ◽  
Avian Retina ◽  
The Magnetic Field

Magnetoreception of the light-dependent magnetic compass in birds is suggested to be mediated by a radical-pair mechanism taking place in the avian retina. Biophysical models on magnetic field effects on radical pairs generally assume that the light activating the magnetoreceptor molecules is nondirectional and unpolarized, and that light absorption is isotropic. However, natural skylight enters the avian retina unidirectionally, through the cornea and the lens, and is often partially polarized. In addition, cryptochromes, the putative magnetoreceptor molecules, absorb light anisotropically, i.e., they preferentially absorb light of a specific direction and polarization, implying that the light-dependent magnetic compass is intrinsically polarization sensitive. To test putative interactions between the avian magnetic compass and polarized light, we developed a spatial orientation assay and trained zebra finches to magnetic and/or overhead polarized light cues in a four-arm “plus” maze. The birds did not use overhead polarized light near the zenith for sky compass orientation. Instead, overhead polarized light modulated light-dependent magnetic compass orientation, i.e., how the birds perceive the magnetic field. Birds were well oriented when tested with the polarized light axis aligned parallel to the magnetic field. When the polarized light axis was aligned perpendicular to the magnetic field, the birds became disoriented. These findings are the first behavioral evidence to our knowledge for a direct interaction between polarized light and the light-dependent magnetic compass in an animal. They reveal a fundamentally new property of the radical pair-based magnetoreceptor with key implications for how birds and other animals perceive the Earth’s magnetic field.

USE OF A SPECIALIZED MAGNETORECEPTION SYSTEM FOR HOMING BY THE EASTERN RED-SPOTTED NEWT NOTOPHTHALMUS VIRIDESCENS

1994 ◽  
Vol 188 (1) ◽  
pp. 275-291 ◽  
Author(s):  
J Phillips ◽  
S Borland
Keyword(s):  
Magnetic Field ◽  
Short Wavelength ◽  
Magnetic Compass ◽  
Compass Orientation ◽  
Full Spectrum ◽  
Long Wavelength ◽  
Magnetic Compass Orientation ◽  
Short Wavelength Light ◽  
The Magnetic Field ◽  
Wavelength Light

Laboratory experiments were carried out to investigate the effects of varying the wavelength of light on the use of an earth-strength magnetic field for shoreward orientation and for the compass component of homing. In the earlier shoreward orientation experiments, newts tested under full-spectrum and short-wavelength (i.e. 400 and 450 nm) light exhibited shoreward magnetic compass orientation. Under long-wavelength (i.e. 550 and 600 nm) light, newts exhibited magnetic compass orientation that was rotated 90 ° counterclockwise to the shoreward direction. This wavelength-dependent shift in magnetic compass orientation was shown to be due to a direct effect of light on the underlying magnetoreception mechanism. In homing experiments, newts tested under full-spectrum and short-wavelength light exhibited homeward magnetic compass orientation. Under long-wavelength light, newts were randomly distributed with respect to the magnetic field. The different effects of long-wavelength light on shoreward orientation and homing confirmed earlier evidence that different magnetoreception systems mediate these two forms of orientation behaviour. The properties of the newt's homing response are consistent with the use of a hybrid magnetoreception system receiving inputs from the light-dependent magnetic compass and from a non-light-dependent intensity (or inclination) detector which, unlike the compass, is sensitive to the polarity of the magnetic field.

Auditory and Magnetic Compass Orientation in C57BL/6 mice

2006 ◽  
Author(s):  
John B. Phillips ◽  
R. Muheim ◽  
N. M. Edgar ◽  
K. S. Sloan
Keyword(s):  
Magnetic Compass ◽  
Compass Orientation ◽  
Magnetic Compass Orientation
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