Best night vision (animal)

A deepsea ostracod crustacean belonging to the genus Gigantocypris has the best night vision of any known animal. In optics, the f-number is a measure of light sensitivity; the smaller the f-number, the wider the lens aperture and hence the greater the amount of light that will enter the eye and fall upon the retina. Whereas the f-number of the human eye is approximately f-2.55, for this crustacean it is an amazing f-0.25, due to its eyes each possessing a pair of high-powered parabolic reflectors directing the very dim light present in its deepsea habitat onto the retina at their centre.