this is how all animals see

 

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Dogs and other animals detect smells using proteins called odorant receptors, chemical sensors. They sit on the surface of cells, grabbing specific molecules that float past. 

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The process is temporary: after the [receptors] are done, they either release or destroy the molecules that they’ve grabbed. But one group of them bucks this trend: opsins. 

They are special because they keep hold of their target molecules, and because those molecules absorb light. This is the entire basis of vision. This is how all animals see—using light-sensitive proteins that are actually modified chemical sensors. 

In a way, we see by smelling light. 

—Ed Yong

An Immense World: How Animal Senses Reveal the Hidden Realms Around Us
(small edits for brevity)

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