Retinal is also known as
retinaldehyde. It was originally called
retinene, and renamed afterwards it was discovered to be
vitamin A aldehyde. Retinal is one of the many forms of vitamin A (the number of which varies from species to species). Retinal is a
polyene chromophore, bound to proteins called
opsins, and is the chemical basis of animal vision. Retinal allows certain microorganisms to convert light into metabolic energy.