Absorption spectrum of the main opsins of the human retina and cryptochrome (CRY) in its oxidized, ground state (in mouse, OPN1SW has a maximal sensitivity at about 360 nm). The bar at the bottom of the graph displays the range of wavelength sensitivity of retinal biorhythms (densely hatched: reported in experiments using light-entrainment; less densely hatched: reported in experiments using light-induced phase shifting). LW: OPN1LW; MW: OPN1MW; SW: OPN1SW [8, 11, 12, 14, 18, 19]