Photoreceptor implicated in non-image-forming responses to light. Expressed in the inner nuclear layer of the retina, possibly in amacrine and ganglion cells. Expressed in a subpopulation of neurons in the dorsal habenula. Expressed in horizontal cell layer of the retina at early larval stages declining to undetectable levels later in development. Belongs to the G-protein coupled receptor 1 family. Opsin subfamily.