Subscribe to our weekly newsletter
Animal magnetism: Bacteria may help creatures sense Earth's magnetic fields
An intriguing theory explains animals' magnetic sense.
- Some animals can navigate via magnetism, though scientists aren't sure how.
- Research shows that some of these animals contain magnetotactic bacteria.
- These bacteria align themselves along the magnetic field's grid lines.
It's one of the more fascinating discoveries of the last several decades: the growing list of animals who can navigate the Earth's magnetic grid to get where they need to go. From birds to dogs, from fruit flies to lobsters, a number of species are somehow hooked into the planet's magnetic field — maybe even humans. The big unanswered question is how?
A new paper just published in Philosophical Transactions of the Royal Society B may have the answer: The creatures may have a symbiotic relationship with magnetotactic bacteria that orient them along global magnetic field lines.
While it's possible that the bacteria themselves are just one more magnetically sensitive organism, the paper presents evidence supporting the theory that their presence within other organisms endows their hosts with their magnetic navigational abilities.
Magnetotactic bacteria hosts
A right whale mother and calf
One of the paper's authors, Geneticist Robert Fitak, is affiliated with the biology department of the University of Central Florida in (UCF) Orlando. Prior to joining the department, he spent four years as a postdoctoral researcher at Duke University investigating the genomic mechanisms responsible for magnetic perception in fish and lobsters.
Fitak tells UFC Today, "The search for a mechanism has been proposed as one of the last major frontiers in sensory biology and described as if we are 'searching for a needle in a needle stack.'"
That metaphorical needle stack may well be the scientific community's largest database of microbes, the Metagenomic Rapid Annotations using Subsystems Technology database. It lists the animal samples in which magnetotactic bacteria have been found.
The primary use of the database, says Fitak, has been the measurement of bacterial diversity in entire phyla. An accounting of the appearance of magnetotactic bacteria in individual species is something that has previously be unexplored. "The presence of these magnetotactic bacteria had been largely overlooked, or 'lost in the mud' amongst the massive scale of these datasets," he reports.
Fitak dug into the database and discovered that magnetotactic bacteria have indeed been identified in a number of species known to navigate by magnetism, among them loggerhead sea turtles, Atlantic right whales, bats, and penguins. Candidatus Magnetobacterium bavaricum is regularly found in loggerheads and penguins, while Magnetospirillum and Magnetococcus are common among right whales and bats.
As for other magnetic-field-sensitive animals, he says, "I'm working with the co-authors and local UCF researchers to develop a genetic test for these bacteria, and we plan to subsequently screen various animals and specific tissues, such as in sea turtles, fish, spiny lobsters and birds."
The bacteria-host relationship
While the presence of the bacteria in these particular species is intriguing, further study is needed to be sure they're responsible for other animals' magnetic navigation. Their presence in these species could be just a coincidence.
Fitak also notes that he doesn't know at this point exactly where in the host animal the magnetotactic bacteria would reside, or other details of their symbiotic relationship. He suggests that they might be found in nervous tissue associated with navigation, such as that found in the brain or eye.
If confirmed, Fitak's hypothesis could suggest that our own sensitivity to the Earth's magnetic field might one day be enhanced via magnetotactic bacteria in our own individual microbiomes, should they be benign to us as hosts.
- Dogs may navigate using Earth's magnetic fields, study shows - Big ... ›
- Birds can see the Earth's magnetic field, scientists say, and this is how ›
- Mystery anomaly is weakening Earth's magnetic field - Big Think ›
A cave in France contains man’s earliest-known structures that had to be built by Neanderthals who were believed to be incapable of such things.
In a French cave deep underground, scientists have discovered what appear to be 176,000-year-old man-made structures. That's 150,000 years earlier than any that have been discovered anywhere before. And they could only have been built by Neanderthals, people who were never before considered capable of such a thing.
Water may be far more abundant on the lunar surface than previously thought.
- Scientists have long thought that water exists on the lunar surface, but it wasn't until 2018 that ice was first discovered on the moon.
- A study published Monday used NASA's Stratospheric Observatory for Infrared Astronomy to confirm the presence of molecular water..
- A second study suggests that shadowy regions on the lunar surface may also contain more ice than previously thought.
Credits: NASA/Daniel Rutter<p>Still, it's not as if the moon is dripping wet. The observations suggest that a cubic meter of the lunar surface (in the Clavius crater site, at least) contains water in concentrations of 100 to 412 parts per million. That's roughly equivalent to a 12-ounce bottle of water. In comparison, the same plot of land in the Sahara desert contains about 100 times more water.</p><p>But a second study suggests other parts of the lunar surface also contain water — and potentially lots of it. Also publishing their findings in <a href="https://www.nature.com/articles/s41550-020-1198-9#_blank" target="_blank">Nature Astronomy</a> on Monday, the researchers used the Lunar Reconnaissance Orbiter to study "cold traps" near the moon's polar regions. These areas of the lunar surface are permanently covered in shadows. In fact, about 0.15 percent of the lunar surface is permanently shadowed, and it's here that water could remain frozen for millions of years.</p><p>Some of these permanently shadowed regions are huge, extending more than a kilometer wide. But others span just 1 cm. These smaller "micro cold traps" are much more abundant than previously thought, and they're spread out across more regions of the lunar surface, according to the new research.</p>
Credit: dottedyeti via AdobeStock<p>Still, the second study didn't confirm that ice is embedded in micro cold traps. But if there is, it would mean that water would be much more accessible to astronauts, considering they wouldn't have to travel into deep, shadowy craters to extract water.</p><p>Greater accessibility to water would not only make it easier for astronauts to get drinking water, but could also enable them to generate rocket fuel and power.</p><p style="margin-left: 20px;">"Water is a valuable resource, for both scientific purposes and for use by our explorers," said Jacob Bleacher, chief exploration scientist in the advanced exploration systems division for NASA's Human Exploration and Operations Mission Directorate, in a statement. "If we can use the resources at the Moon, then we can carry less water and more equipment to help enable new scientific discoveries."</p>