Retinal

Retinal is a polyene chromophore which is bound to proteins called opsins and provides the chemical basis for animal vision. It can also be callled retinaldehyde or vitamin A aldehyde and it is one of three forms of vitamin A. Retinal is bound to type 1 rhodopsins and it allows organisms to convert light into metabolic energy. Animals can ingest retinoids through eating meat or can produce it from eating carotenes (alpha or beta) which they must obtain from plants or other photosynthetic organisms.