Special Molecule Gives Birds a Magnetic Biocompass

Aaron Rowe writes "CORDIS news reports that a team of scientists has identified a family of molecules called cryptochromes that allow migratory birds to sense magnetic fields. Curiously enough, these molecules only function when accompanied by blue light. The article also mentions, 'The researchers also suggest that, as cryptochromes have been strongly conserved throughout evolution, all biological organisms could have the ability to detect magnetic fields, even if they do not use them.'"

Comments

My brother-in-law does sense it

[WindBourne]

When he gets off the plane at DIA, his first question is which way to north. Once he has his berings, he always knows his directions. Even when traveling through the mountains, day or night, he is able to figure out the direction quickly. Pretty impressive. What I find interesting is that plane travels screws him up. Once on the ground, If he does not get his bearing quickl, he appears to get more uncomfortable as time passes.

Re:My brother-in-law does sense it

[smilindog2000]

We do have a built-in gyroscope, though not a compass. I'm pretty sure guys have a stronger sense of it then girls. Makes sense... hunting and all.

I have a good sense of direction, but now and then I get all messed up. It's a really strange feeling when I realize this has happened, and the internal gyro has to flip 180 degrees. There's a sense of the world shifting, almost like motion.

Where will the birds go during a pole reversal?

[smilindog2000]

I hope they don't get too confused:

http://science.slashdot.org/article.pl?sid=04/05/1 5/1544240
http://digg.com/general_sciences/North_Pole_Moving _South_

No wonder those latent genes are turned off.

Detecting Changing Magnetic Fields

[DrLudicrous]

Anecdotally, I have heard of many people "sensing" the magnetic field of an MRI scanner. I have had a few MRI's done on myself, and can attest to this feeling. It is strange, mostly in the head, somewhat like when one feels dizzy or just a tinge of seasickness. I think that is has something to do with the fact that as you enter the scanner, the field you experience changes quite rapidly. Once you are in the scanner, I haven't really noticed the queasiness as much, though it still feels strange. However, I attribute this second sensation more to the fact that one is contained inside a small tube with all kinds of weird noises and vibrations going around. So at the very least, some people seem to be sensitive to changing fields above some threshold.

Why Blue Light?

[NexFlamma]

They mention the blue light necessity of this system, but they never really explain why it has to be blue light or what the light itself does (unless I've become illiterate). Can anyone explain (or at least make something plausible up) the whole blue light component of this mechanism?

Re:Why Blue Light?

[IorDMUX]

The current theory is that certain (blue-ish) frequencies of light create radical pairs--charged particles--that are affected by the Earth's magnetic field. Some (unkown, I believe) mechanism detects the effect on these particles (perhaps a Hall voltage?) and interprets that as magnetic field information.

red light causes a disruption,,, interesting

[Anonymous Coward]

I've know for a long time that many large birds freak out when a red laser pointer is shown anywhere near them. Especially large parrots. I'm not talking about pointing in their eyes, which is cruel to any animal. But just shining the red light nearby is enough to agitate them, and if shown near their head they will lose balance and fall from their tree.

These light sensitive molecules must be very important to the bird's balance as well as helping them migrate. I wonder if they use the magnetic field to remain upright as well, or if by the red light turning off the receptor magnetic-sensitive light receptor molecules, they temporarily go blind. REd light could be perceived to be much brighter to them than the other colors. Since if the red light shuts off the receptors, only a small amount must be blinding. It might be like flipping a light switch where all blue and green perception disappears and only red is left. I"m glad my eye's aren't affected by specific colors that way.

Birds also follow their noses

[Splinton]

According to a recent New Scientist article, homing pigeons use their nose to find home rather than the Earth's magnetic field.

From the article:

She released 48 inexperienced homing pigeons 50 kilometres from their home loft. Half of them had had their olfactory nerve severed and half their trigeminal nerve, which is responsible for magnetic navigation. The next day, all but one of the birds deprived of their trigeminal nerve had returned home. Only four without a sense of smell returned (The Journal of Experimental Biology, vol 209, p 2888).