Life Lines is a general interest science podcast of The American Physiological Society dedicated to conveying the "phizz" in physiology.
No, we are not talking about mating habits here. We are talking about the ability of some animals to use the Earth's magnetic field to navigate and in the case of foxes, to find prey. In a recent article published in New Scientist, foxes have been identified as the first animal believed to use the Earth's magnetic field for more than simply determining which direction they are heading. While Dr. Hynek Burda from the University of Duisburg-Essen, Germany was observing the animals, he noticed that when the prey was hidden, the foxes almost always jumped on their prey in a northeast direction resulting in a 72% success rate of capturing prey, compared to only 18% when the jumps were in a random direction. Dr. John Phillips at Virginia Tech in Blacksburg suggested that the foxes might be using the Earth's magnetic field to estimate distance. These findings are still rather speculative, but definitely warrant further study.
It is well-known that some migratory animals such as birds, loggerhead turtle hatchlings, blind mole rats, salmon, lobsters, hamsters, bacteria, etc., may use the Earth's magnetic field for navigation (much like we use compasses to determine our direction). In fact, it is thought that birds use the magnetic field to plan out their migratory route including where to stop for a bite to eat.
In this video you can see just how sensitive sharks are to magnetic fields which may help them to navigate and find prey.
Herd animals do it too. You can hear all about how cows and deer are able to use the Earth's magnetic field to align their bodies in a north-south direction while grazing or resting.
Even butterflies do it, but in an apparently novel way. A recent article published by ScienceDaily, highlighted the work of Drs. Steven Reppert, Robert Gegear, and Amy Casselman on how monarch butterflies may use a photoreceptor (cryptochrome, Cry2) to sense the Earth's magnetic field. Flies may use a similar Cry1 photoreceptor for magnetoreception. The researchers note that the butterfly Cry2 photoreceptor is related to the receptor found in vertebrates suggesting that migratory vertebrates may also use this photoreceptor to sense magnetic fields.
So what happens if the Earth's magnetic field shifts? You might just have to read about it on Nova.
Image Source: Jumping Fox via Flickr/ Mike Baird
Life Science
Comments
The earth's magnetic field gives a fox no information about distance or location of its prey.
Higher success pouncing in one direction more likely has to do with wind and sunlight directions.
Posted by: Rick Miller | February 4, 2011 11:35 AM
The following statement from the post is false,"foxes have been identified as the first animal believed to use the Earth's magnetic field for more than simply determining which direction they are heading". Several organisms have been shown to use the GMF to estimate geographic position in addition to using it for directional or compass orientation.
The conclusion that the foxes are relying on magnetic info seems like quite a "leap" given the number of other possible mechanisms at play.
Posted by: Larry Boles | February 6, 2011 2:38 PM