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Earth as a Magnet

Earth has magnetic poles and a magnetic field over which it exerts magnetic force.

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There’s No Place Like Home

How do birds, butterflies, and other migratory animals find their ways home?

Credit: Vampire Bear
Source: http://www.flickr.com/photos/vampire_bear/42692169/sizes/m/in/photolist-4LNTT-5ufv8-7VDb8-iMjTP-xcrKC-HTMwk-2HFe6S-4jVe4p-4kQgdG-4mKzFS-4vHyQ6-4vMxAh-4FPUPu-5SWf66-5VpLNF-6wgJv3-79bi7L-7pJDFt-dYzLQe-bD9uvG-dixRzF-9o5Fe7-bpUB3N-dMccBE-bn8JVa-7CWGYV-aSq5zT-7BqTLx-dHktD8-7GrKYh-8q7dmD-7AyFfN-b88ET2-bB5vi4-9iViFZ-9iVoRx-9iVmJi-9iVsB2-9iVpTx-9iYzxS-9iVqAx-9iYvN3-9iYtBw-9iVhqr-7D8n1j-98BS9m-7AyEi7-9sNbAV-9sQRGf-b62EUK-7C9gnT/
License: CC BY-NC 3.0


A protein called cryptochrome is found in migratory animals and may help animals geomagnetically orient themselves using light; it may allow animals to “see” Earth’s magnetic field.  One theory of how cryptochrome works has to do with its structure.  The cryptochrome comes in pairs and Earth’s magnetic field causes one of its electrons to move.  The animal can sense Earth’s magnetic field in relation to the movement of cryptochrome’s electrons.  Humans have a large amount of cryptochrome in their eyes, insinuating that humans may have been able to “see” Earth’s magnetic field a long time ago.  The human version of cryptochrome is able to restore geomagnetic orientation in fruit flies, so if it is able to help fruit flies orient themselves to Earth’s magnetic field it may be able to do so in humans as well.  However, in order for cryptochrome to function it needs superoxide, a free radical that damages DNA.  This is very dangerous for long-living organisms and may be why humans do not activate it currently.

Creative Applications

  1. If you could see Earth’s magnetic field, what do you think it would look like?
  2. What are theories? How come these thoughts about cryptochrome are theories and not hypotheses?
  3. What are some other ways that animals can use geomagnetic orientation? (Hint: Foxes have been known to use geomagnetic orientation for activities other than migration.)





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