Bacteria: Magnetite Crystals, Movement & Earth's Magnetic Field

[JimmyRay]

What do magnetite crystals found in some bacteria exactly do? I heard it helps them move around but, how would that work? Can they not move on their own? Are they always only affected by the Earth's magnetic field?

 

[Ouabache]

What do magnetite crystals found in some bacteria exactly do? I heard it helps them move around but, how would that work? Can they not move on their own? Are they always only affected by the Earth's magnetic field?

I imagine your question was promted by a related thread
the magnetite crystals actually form dipoles with two polar ends just like a compass needle. Presumably the bacteria that contain these crystals are influenced by the orientation of the crystals and can decide whether to base its direction of movement, using it's internal compass or not.. (After all birds who have magnetite in their heads don't always move north or south). In the case of the bacteria, there are other mechanisms that also influence their movement: temperature, pH gradient, moisture, food (chemotactic), gravity.. But certainly an internal compass makes a nice addition to its sensors.

 

[JimmyRay]

Ohh I see...thats pretty cool, actually that question just came up in physics class lol, we're studying electricity and magnetism I just wanted some more insight... I'll check out the thread though thanks...