Visual Behavior and Visual Sensitivity of Nautilus pompilius

Abstract

The various species of Nautilus found today show many features that are probably primitive. Of them, the eye has attracted attention because it has no lens and appears to operate on the principle of a pinhole camera; consequently, it should have a performance considerably inferior to that of the lens-bearing eyes of other cephalopods. This inferiority was confirmed for visual acuity in a previous paper (Muntz and Raj, 1984). It was found, using the optomotor response, that the minimum separable angle lay between 5.5 and 11.25°, which agreed well with the value expected on the basis of the gross dimensions of the eye and also with expectations based on photographing a visual test chart with a scale model of the eye. In Octopus vulgaris, on the other hand, the minimum separable visual acuity is 17° or better (Sutherland, 1963).