Coexpressed Opsins

Two different opsins (with different peak wavelengths) that occupy the same photoreceptor.

This is one reason that the number of opsins in an organism’s genome, or the number of opsins expressed are not perfect indicators of the ‘depth’ of color vision.

For example, a mantis shrimp was briefly considered to have the most opsins and therefore the ‘richest’ color vision. However, it was later determined that many of those opsins are co-expressed in the same photoreceptor, and so don’t provide independent, comparable signals that can be used to determine color.