Magnetoreception: The Uses of Earth’s Magnetic Field

We have a lot of senses in common with other animals. ¹ However, some senses are completely closed to human perception. Magnetoreception, or the perception of a magnetic field, is one example. In Ecology class last semester, I learned that ants can use our planet’s magnetic field to find their way back to the nest. Even so, Magnetoreception is used by a variety of animals. ¹ Therefore, I will explore magnetoreception and the uses of the earth’s magnetic field in this blog post.

What is magnetism?

According to the National Geographic “Magnetism is caused by the motion of electric charges”. But where does the electric charge come from? All substances consist of small units, the atoms. Each atom possesses a positively charged core in the middle surrounded by negatively charged electrons. The electrons are circulating around the core creating an electric current. Most substances have an equal number of electrons spinning in opposite directions, cancelling out their magnetism. For example, paper is only weekly magnetic. ²

Why is there a magnetic field on Earth?

So far, we’ve learned that the motion of magnetic charges produces a magnetic field. The following question is, what causes this electric motion on Earth? The Earth’s outer core is made up of molten metal. Scientists have not yet fully understood why, but the motion of this fluid creates electric currents. Et voila we have our magnetic field, which extends around the entire planet due to the Earth’s rotation around its axis.  ^{2 3}

If this explanation was a little too quick for you, you can watch it again in the video below.

How migratory animals use magnetoreception

Animals use the magnetic field in different ways. ¹ Sea turtles migrating across the North Atlantic, encountering various magnetic fields along the way. ⁴ The turtles’ system is based on variations in the magnetic field giving each geographic area a unique magnetic pattern. ⁵ These fields, which act as boundaries, are detected by the turtles and used to keep them on course. ⁴ The research suggests a strategy for guiding “one of nature’s longest migrations” (Brown, 2001).

If you want to learn more about sea turtles, check out my 5 amazing facts about sea turtles blog post.

Other animals that use magnetoreception

Other animals that use the magnetic field to navigate include bees, salmon, and pigeons. ² Scientists assume they might “have magnetic material in their bodies that acts like a compass” (National Geographic, s.a.).

Conclusion

Magnetism is produced by electric currents. This current is generated on Earth by molten metal in the outer core. Migratory animals such as sea turtles and salmon use our planet’s magnetic field to navigate.

References:

1. Xie, C., 2022. Searching for unity in diversity of animal magnetoreception: From biology to quantum mechanics and back. The Innovation. Volume 3, Issue 3.
2. National Geographic, s.a. Magnetism. Available at: https://education.nationalgeographic.org/resource/magnetism [16.01.2023].
3. Cosmoknowledge, 2020. Why Does Earth Have A Magnetic Field? Youtube. Available at: https://www.youtube.com/watch?v=MtLC8evycaE [16.01.2023].
4. Brown, K., 2001. Animal Magnetism Guides Migration. Science. Volume 294, Issue 5541. 283-284.
5. National Science Foundation, 2004. Geomagnetic Landmarks Give Turtles Sense of Where They Are, Where to Go. Available at: https://beta.nsf.gov/news/geomagnetic-landmarks-give-turtles-sense-where [16.01.2023].