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How do animals & bacteria sense compass direction?

  1. Nov 21, 2005 #1


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    You are probably aware of migratory behavior of birds. But what is the mechanism that accounts for this?

    It is based on a unique biochemistry that incorporates ferromagnetic material (magnetite) within them and utilizes their orientation to govern its spatial movement (horizontal and vertical). Outside of migration behavior, other examples of orientation behavior due to magnetite, occur across the animal kingdom: honey bees, homing pigeons, sharks, dolphins, newt, rainbow trout, salmon. Even certain bacteria e.g. Magnetospirillum gryphiswaldense exhibit this. Researchers found stable needle-like strands of magnetite crystal (magnetic dipoles) in these bacteria.
    Last edited: Nov 21, 2005
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  3. Nov 22, 2005 #2
  4. Nov 22, 2005 #3


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    Nice one gerben!! The bobolinks (and a few other species) sure have evolved quite an impressive mechanism for direction finding :biggrin:

    So the hundred dollar question is, how does the magnetite interface with the brain, so that it senses magnetic polar direction? Does the brain compare magnetic field to a spatial map comprised of brain cells? :uhh:

    Do we have any neuroethologists here on PF?

    Quote from gerben's reference:
    "Like any good pilot, the bobolink carries a compass. Recent research suggests that cells in the bird's head contain magnetite, an iron oxide crystal that aligns with magnetic north like a tiny compass needle. Scientists think these cells may serve as receptors that send directional information to the brain. Many other animals apparently also have such cells: Magnetite has been found in the heads of migratory fish, sea turtles and humpback whales. Of all the wildlife navigators, birds so far are the best studied."
    Last edited: Nov 22, 2005
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