Animals' / Humans' Magnetic Sensory Abilities

[EnolaGaia]

Here are the bibliographic details and abstract from the 2020 research article cited in the Science Alert article.

Symbiotic magnetic sensing: raising evidence and beyond
Eviatar Natan, Robert Rodgers Fitak, Yuval Werber and Yoni Vortman
Philosophical Transactions of the Royal Society B: Biological Sciences
Volume 375, Issue 1808
Published:10 August 2020
https://doi.org/10.1098/rstb.2019.0595

Abstract

The identity of a magnetic sensor in animals remains enigmatic. Although the use of the geomagnetic field for orientation and navigation in animals across a broad taxonomic range has been well established over the past five decades, the identity of the magnetic-sensing organ and its structure and/or apparatus within such animals remains elusive—‘a sense without a receptor’. Recently, we proposed that symbiotic magnetotactic bacteria (MTB) may serve as the underlying mechanism behind a magnetic sense in animals—‘the symbiotic magnetic-sensing hypothesis'. Since we first presented this hypothesis, both criticism and support have been raised accordingly. Here we address the primary criticisms and discuss the plausibility of such a symbiosis, supported by preliminary findings demonstrating the ubiquity of MTB DNA in general, and specifically in animal samples. We also refer to new supporting findings, and discuss host adaptations that could be driven by such a symbiosis. Finally, we suggest the future research directions required to confirm or refute the possibility of symbiotic magnetic-sensing.

This article is part of the theme issue ‘The role of the microbiome in host evolution’.

SOURCE: https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0595

 

[EnolaGaia]

German researchers have determined mole-rats' magnetic-sensing capabilities are based in their otherwise nearly useless eyes.

Virtually Blind Mole-Rats Use Their Eyes to 'See' Magnetic Fields, Experiment Shows

In the gloom of subterranean tunnels, chonky little mole-rats build their nests, tucked safely away, deep inside the earth. Strangely, one species always carefully builds these nests in the south-eastern part of their den.

Why they do this remains unclear, but even in total darkness, it seems, these burrowing rodents – animals that can barely see in the best of conditions – can still sense direction.

We've long known animals like birds can sense magnetic fields, and recently discovered dogs navigate via them too. But the biological mechanisms behind this sense – and how it might function in mole-rats – are still very much a mystery. We didn't even know where in the body these magnetic detectors, whatever they prove to be, are located.

A recent theory suggests this sensory ability may somehow occur via magnetotactic bacteria living within these species. But so far clues about mole-rats' magnetoreceptors suggest that their mechanism is magnetite-based.

This sense of Earth's magnetic field works independent of light, and is affected by strong magnetic pulses but not radio frequencies, explain researchers from the University of Duisburg-Essen in Germany. They've been studying Ansell's mole-rat (Fukomys anselli) to learn more about how this sensory mystery works. ...

"We conclude that the removal of the eyes led to a permanent impairment of the magnetic sense," the team write. "Our study is the first to identify a magnetoreceptive organ in a mammal."

Caspar and team suggest the eyes be closely examined under electron-microscopy and through spectroscopy to find these elusive mammalian magnetoreceptors. ...

FULL STORY: https://www.sciencealert.com/almost-blind-mole-rats-use-their-eyes-to-see-magnetic-fields

 

[EnolaGaia]

Here are the bibliographic details and abstract for the published paper on the German work.

Eyes are essential for magnetoreception in a mammal
Kai R. Caspar , Katrin Moldenhauer , Regina E. Moritz , Pavel Němec , E. Pascal Malkemper and Sabine Begall
Journal of the Royal Society Interface
Published: 30 September 2020
https://doi.org/10.1098/rsif.2020.0513

Abstract
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.

SOURCE: https://royalsocietypublishing.org/doi/10.1098/rsif.2020.0513

 

[IbisNibs]

This 2017 paper proposed the radical idea that animals' magnetic sensory capabilities (magnetoreception) might be the result of symbiotic cooperation with magnetism-sensitive (magnetotactic) microbes within their bodies.

The symbiotic magnetic-sensing hypothesis: do Magnetotactic Bacteria underlie the magnetic sensing capability of animals?
Eviatar Natan and Yoni Vortman

Where is the dietary supplement based on a pseudoscientific version of this theory?
Will it be on tap at favorite breweries and pubs?
Improves your sense of direction! You'll never get lost on your way home again!

 

[EnolaGaia]

Newly published research results strongly suggests sharks are sensitive to, and orient themselves with respect to, magnetic fields.

New Evidence Suggests Sharks Use Earth’s Magnetic Field to Navigate

Every December, great white sharks swimming off the coast of California make a beeline for a mysterious spot in the middle of the Pacific roughly halfway to the Hawaiian islands. The sharks travel roughly 1,000 miles to the so-called white shark cafe. Tracking data has revealed that their routes are remarkably direct considering their paths traverse apparently featureless open ocean. Tiger sharks, salmon sharks and multiple species of hammerheads also make lengthy journeys to and from precise locations year after year.

Pete Klimley, a retired shark researcher who worked at the University of California, Davis calls the ability of some animals to find their way to pinpoint locations across the globe “one of the great mysteries of the animal kingdom.”

Now, new research published today in the journal Current Biology provides new support for a longstanding hypothesis that sharks use the Earth’s magnetic field to navigate during their long-distance migrations. Scientists caught bonnethead sharks off the coast of Florida and put them in a tank surrounded by copper wires that simulated the magnetic fields sharks would experience in locations hundreds of miles from their home waters. In one key test, the bonnetheads were tricked into thinking they were south of their usual haunts and in response the sharks swam north. ...

FULL STORY:
https://www.smithsonianmag.com/scie...use-earths-magnetic-field-navigate-180977668/

PUBLISHED RESEARCH REPORT:
Map-like use of Earth’s magnetic field in sharks
Bryan A. Keller, Nathan F. Putman, R. Dean Grubbs, David S. Portnoy, Timothy P. Murphy
Current Biology, May 06, 2021
DOI:https://doi.org/10.1016/j.cub.2021.03.103

Full Article Accessible At: https://www.cell.com/current-biolog...m/retrieve/pii/S0960982221004760?showall=true