Short Communications: The Spectral Sensitivity of Nautilus Pompilius

Abstract

Recent studies (Muntz & Raj, 1984; Muntz, 1986) have measured the visual acuity and sensitivity of Nautilus pompilius, using two behavioural responses (the optomotor response and the positive phototactic response) which are well developed in this species. In both cases, as might be expected for an animal that has a pin-hole camera eye, vision was poor compared to that of animals that have camera eyes with lenses. Thus for visual acuity it was found that the minimum separable angle lay between 1·25° and 5·5°, compared with values between 4·9′ and 10·8′ for various species of fish (Muntz, 1974), and a value of 17′ or better for Octopus vulgaris (Sutherland, 1963), and the absolute sensitivity was estimated to be around 2 log units worse than for a typical deep-sea fish.