How can some animals see through dark while no light is reaching their eyes?
Most jungle animals as well as deep ocean ones have way much better capacity to see in the dark than humans. Some of them have broader wavelength spectrum sensitivity while others has just more sensitivity to light. Photosensitive ganglion cells, also called photosensitive Retinal Ganglion Cells (pRGC), intrinsically photosensitive Retinal Ganglion Cells (ipRGC) or melanopsin-containing ganglion cells, are a recently discovered type of nerve cell in the retina of the mammalian eye which, unlike other retinal ganglion cells, are intrinsically photosensitive. This means that they are a third class of retinal photoreceptors, excited by light even when all influences from classical photoreceptors (rods and cones) are blocked (either by applying pharmacological agents or by dissociating the ganglion cell from the retina). Photosensitive ganglion cells contain the photopigment melanopsin. The giant retinal ganglion cells of the primate retina are examples of photosensitive ganglion cells.
