by Athena Cai
After a salmon is born in a river, it will migrate to the ocean. The fish may live here for one to seven years before journeying back to where it first spawned. How are these fish and other migratory animals able to find their way back home after so long?
The discovery of a natural response in animals to the earth’s magnetic field called magnetoreception left researchers amazed. Apart from salmon, this magnetic sense has also been found in insects, birds, whales, turtles, wolves, and even plants. Magnetoreception not only allows these animals to locate North, but also to map their location. Using this sense of direction, migratory animals are able to retrace their routes and navigate the world. Currently there are a few explanations to how magnetoreception works.
Magnetite is the most magnetic naturally occurring rock mineral on Earth and exists in bird beaks and fish noses. With its magnetic qualities, this mineral could serve as a biological compass. However, the neural system of an animal does not actually respond to magnetite. Researchers have yet to find a case where this mineral serves the purpose of acting as a magnet sensor. Even so, science still regards the presence of magnetite as a plausible explanation.
Another potential explanation for magnetoreception are cryptochrome molecules that bond with MagR, a protein, to form clumps. These clumps orient themselves like a compass needle based on the surrounding magnetic field. This causes the nervous system to give the animal cues about its location. This explanation is still a hypothesis, researchers are still studying the effects of these proteins on animals.
Today, the explanation behind magnetoreception remains a mystery that still has researchers puzzled. The next time our family goes to watch the salmon during spawning season; I’ll be sure to appreciate the biological phenomenon that made it all possible.
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