Magnetoreception: Difference between revisions

Latest revision as of 17:27, 5 December 2015

By Nicholas Chen

Magnetoreception is the ability of certain organisms to detect magnetic fields in order to get a sense of direction or location. Many animals have shown the ability to use the Earth's magnetic field to orient themselves and gain information about their surroundings. These include salmon, sea turtles, lobsters, fruit flies, and most notably birds which use this sensory function to migrate.

Background

The basis of magnetoreception comes from the Earth's magnetic field, which presents itself as a large dipole with a magnetic north and a magnetic south. Because of its polarized nature, magnetic fields radiate outwards from the earth in a looping pattern. These magnetic "fields lines" are what organisms use to orient themselves. However, the details behind the physiological mechanisms for magnetic field detection are still elusive. The exact sensory organ or body part in homing pigeons for example has not been determined, but neurons have been shown to be sensitive to geomagnetic fields and take into account aspects like direction, polarity, and intensity.

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Mechanisms

Although the existence of magnetoreception was plagued by suspicion for many years, a clear example of an organism making use of the Earth's magnetic fields is found in the bacterium Magnetobacterium bavaricum. After investigation, the bacterium was found to have crystals of [math]\displaystyle{ Fe_{3}O_{4} }[/math] or magnetite inside its cells, which all polarize in the direction of present magnetic fields, forming a chain. This gives the bacterium magnetic characteristics and allows the cell to consistently travel along these magnetic field lines. The necessary length of magnetite to become magnetized and sensitive to effects of magnetic fields is extremely small- 50 nm.

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Other organisms possess electroreceptive organs which can detect electric fields. However, these animals could potentially also detect magnetic fields through Faraday's Law. The time-varying change in flux could generate an electric potential.

A Mathematical Model

[math]\displaystyle{ V_{system}= -{\frac{dϕ}{dt}} }[/math]

Using this equation, the electric potential can be found by treating the animal moving through the Earth's magnetic field as a conductor over a period of time.

Difficulties with progress

There are many difficulties detecting the exact sensory receptor in charge of magnetoreception. Multiple factors including the use of other animal senses like sight, the physical size of such a receptor, and combined mechanisms make it hard to pinpoint the various effects. Furthermore, the purpose of magnetoreception is unclear as well, whether animals use it to navigate or create a familiarity "map".

External links

[1]

[2]

[3]

References

S.H.K. Eder et al., “Magnetic characterization of isolated candidate vertebrate magnetoreceptor cells,” PNAS, 109:12022-27, 2012

L.Q. Wu, J.D. Dickman, “Neural correlates of a magnetic sense,” Science, 336:1054-57, 2012.

C.D. Treiber et al., “Clusters of iron-rich cells in the upper beak of pigeons are macrophages not magnetosensitive neurons,” Nature, 484:367-70, 2012.

@@ Line 1: / Line 1: @@
+By Nicholas Chen
-Magnetoreception is the ability of certain organisms to detect magnetic fields in order to get a sense of direction or location. Many animals have shown the ability to use the Earth's magnetic field to orient themselves and gain information about their surroundings. These include salmon, sea turtles, lobsters, fruit flies, and most notably birds which use this sensory function to migrate.
+Magnetoreception is the ability of certain organisms to detect magnetic fields in order to get a sense of direction or location. Many animals have shown the ability to use the Earth's magnetic field to orient themselves and gain information about their surroundings. These include salmon, sea turtles, lobsters, fruit flies, and most notably birds which use this sensory function to migrate. [[File:pigeon.jpg|thumb|right]]
 ===Background===
-The basis of magnetoreception comes from the Earth's magnetic field, which presents itself as a large dipole with a magnetic north and a magnetic south. Because of its polarized nature, magnetic fields radiate outwards from the earth in a looping pattern. These magnetic "fields lines" are what organisms use to orient themselves.   [[image:http://www.the-scientist.com/images/August2013/Globe400x357_1.jpg
+The basis of magnetoreception comes from the Earth's magnetic field, which presents itself as a large dipole with a magnetic north and a magnetic south. Because of its polarized nature, magnetic fields radiate outwards from the earth in a looping pattern. These magnetic "fields lines" are what organisms use to orient themselves. However, the details behind the physiological mechanisms for magnetic field detection are still elusive. The exact sensory organ or body part in homing pigeons for example has not been determined, but neurons have been shown to be sensitive to geomagnetic fields and take into account aspects like direction, polarity, and intensity.
+[[File:Globe400x357 1.jpg|thumb|right]]
-]]
+===Mechanisms===
-Although the existence of magnetoreception was plagued by suspicion for many years, a clear example of an organism making use of the Earth's magnetic fields is found in the bacterium Magnetobacterium bavaricum. After investigation, the bacterium was found to have magnetite crystals inside its cells, which all polarize in the direction of present magnetic fields, forming a chain. This gives the bacterium magnetic characteristics and allows the cell to consistently travel along these magnetic field lines.
-http://www.the-scientist.com/images/August2013/feature_pic13.jpg
+Although the existence of magnetoreception was plagued by suspicion for many years, a clear example of an organism making use of the Earth's magnetic fields is found in the bacterium Magnetobacterium bavaricum. After investigation, the bacterium was found to have crystals of <math>Fe_{3}O_{4}</math> or magnetite inside its cells, which all polarize in the direction of present magnetic fields, forming a chain. This gives the bacterium magnetic characteristics and allows the cell to consistently travel along these magnetic field lines. The necessary length of magnetite to become magnetized and sensitive to effects of magnetic fields is extremely small- 50 nm.
+[[File:Feature_pic13.jpg|thumb|right]]
+Other organisms possess electroreceptive organs which can detect electric fields. However, these animals could potentially also detect magnetic fields through Faraday's Law. The time-varying change in flux could generate an electric potential.
 ===A Mathematical Model===
-What are the mathematical equations that allow us to model this topic.  For example <math>{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}</math> where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.
+<math> V_{system}= -{\frac{dϕ}{dt}}</math>
-===A Computational Model===
+Using this equation, the electric potential can be found by treating the animal moving through the Earth's magnetic field as a conductor over a period of time.
-How do we visualize or predict using this topic. Consider embedding some vpython code here [image:https://trinket.io/glowscript/31d0f9ad9e Teach hands-on with GlowScript]
+==Difficulties with progress==
-==Examples==
+There are many difficulties detecting the exact sensory receptor in charge of magnetoreception. Multiple factors including the use of other animal senses like sight, the physical size of such a receptor, and combined mechanisms make it hard to pinpoint the various effects. Furthermore, the purpose of magnetoreception is unclear as well, whether animals use it to navigate or create a familiarity "map".
-Be sure to show all steps in your solution and include diagrams whenever possible
+===External links===
+[https://en.wikipedia.org/wiki/Magnetoreception]
-===Simple===
-===Middling===
-===Difficult===
-==Connectedness==
-#How is this topic connected to something that you are interested in?
-#How is it connected to your major?
-#Is there an interesting industrial application?
-==History==
-Put this idea in historical context. Give the reader the Who, What, When, Where, and Why.
+[http://www.ks.uiuc.edu/Research/cryptochrome/]
-== See also ==
+[http://www.nature.com/news/pigeons-may-hear-magnetic-fields-1.10540]
-Are there related topics or categories in this wiki resource for the curious reader to explore?  How does this topic fit into that context?
+===References===
-===Further reading===
-Books, Articles or other print media on this topic
-===External links===
-[http://www.scientificamerican.com/article/bring-science-home-reaction-time/]
+S.H.K. Eder et al., “Magnetic characterization of isolated candidate vertebrate magnetoreceptor cells,” PNAS, 109:12022-27, 2012
-==References==
+L.Q. Wu, J.D. Dickman, “Neural correlates of a magnetic sense,” Science, 336:1054-57, 2012.
-This section contains the the references you used while writing this page
+C.D. Treiber et al., “Clusters of iron-rich cells in the upper beak of pigeons are macrophages not magnetosensitive neurons,” Nature, 484:367-70, 2012.
 [[Category:Which Category did you place this in?]]