Magnetoreceptors

Evidence for an ability to alter their behavior in response to the earth's magnetic field has been found in many animals, including as well as in some bacteria [Link].

Some examples:

How Do They Do It (i.e. what receptors detect magnetic fields)?

The location and mechanism of action of the receptors in these animals is still a puzzle. Microscopic grains of magnetite (FeO.Fe2O3), a magnetic material, have been found in honeybees and pigeons, but whether and how these might function as receptors is not known.

Certain bacteria orient themselves in magnetic fields as weak as those of the earth and this is mediated by grains of magnetite within the cell.

Link to view of magnetic grains in a bacterium.

There is also evidence that birds and amphibians can supplement their magnetic sense using the interaction of light and magnetic fields on cryptochrome molecules in their retina.

The ability of Drosophila to respond to magnetic fields depends on blue light and cryptochrome.

What About Humans?

The jury is still out.

There is some evidence that humans can detect the orientation of magnetic fields. Both cryptochrome and magnetite are found in humans, but their presence may have nothing to do with magnetoreception.

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1 July 2016