Salmon’s built-in compass*

Published May 4, 2020

How do salmon know how to get back from the ocean to the exact place they spawned when it’s time to make sweet, sweet love again? Built-in mag­nets, of course. Well, “micro­scop­ic crys­tals of mag­netite in their tis­sue” to be specific.

“[T]hese salmon know where they are, where they’re sup­posed to be, how to get there and how to make cor­rec­tions if need­ed. While they’re in fresh water, they’re imprint­ing upon the chem­i­cal nature of the water. When they hit salt water, they switch over to geo­mag­net­ic cues and lock in that lat­i­tude and lon­gi­tude, know­ing they need to come back to those coordinates.”

Pro tip: If you’re ever lost in the woods, you can use a salmon as a compass.

* For you kids: A compass is what people used to use before we had GPS.
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