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Scientists Found a “Bio Compass” in Birds’ Eyes

Birds orient their far flying using the Earth’s magnetic field: some species successfully.fly for more than thousands of miles during their seasonal migration.

Birds and Compass

For a long time, scientists thought that birds werere able to use the magnetic field for navigation because of iron links: there are lots of such connections near their beaks. But in recent years, there were more and more marks appearing, saying that the point is not about “iron beaks” but about a special type of proteins which is synthesized in cells of some eye tissues.

Two new articles, published in Journal of the Royal Society Interface and Current Biology journals, scientists describe a certain protein – Cry4 – which is responsible for the “sixth sense” of birds. It was found in the eye retina of little birds called robins and some other species. If the conclusions of the researchers are correct, then this is the first protein which could be connected with the animals’ magnetic feelings.

Cry4 belongs to the crypochrome class: these proteins are sensitive to light, they let us see blue colors, and some animals can even notice the ultraviolet part of the specter. In addition, cryptochromes take part in circadian rhythm regulation. It seems that a part of these proteins is sensitive to the magnetic field. The reaction of its molecule to the magnetic field is possibly caused by quantum-level processes.

To find the protein responsible for the magnetic feeling, scientists have investigated retina, eye muscle and brain cells of 39 zebra finches (Taeniopygia guttata) – popular laboratory birds. There were three “suspected” proteins: Cry1, Cry2 and Cry4.

The concentration of first two proteins depended on the day period, while that of the Cry4 remained stable. One of the research authors, the biologist Rachel Muheim, explained that scientists based on the fact that birds rely on their magnetic feeling both during the day and the night.

The second group of scientists have found out that the concentration of Cry4 protein remains stable in the organism of a robin, too.  Adipose tissue cells of robins, which receive enough solar light, produce especially big amounts of this protein. Possibly, this helps Cry4 function like a compass.

Biology Bird

These conclusions give the basis to suppose that the Cry4 protein participates in bird’s magnetic navigation. But to know that for sure, scientists need to find birds with cells not synthesizing Cry4 and to find out if their “compass” functions properly. So, the question about how exactly birds feel the magnetic field of a planet, remains open.