Visual pigment of the freshwater stingray, paratrygon motoro

Abstract

IN general the absorbance spectra of the visual pigments of deep-water and pelagic marine animals are blueshifted compared to those of coastal and estuarine animals, and the pigments of the latter are blueshifted compared with those of freshwater animals. This trend, which correlates with the transmittances of the waters, is best documented for the Osteichthyes (bony fishes)1. The marine members of this Class, except for some wrasses, have visual pigments based on vitamin A1 (rhodopsins of λmax 473 to 512 nm). In freshwater Osteichthyes, however, the need for longer-wave sensitivity is met by pigments based on vitamin A 2 (porphyropsins of λmax 523 to 543 nm) or by mixtures of porphyropsin and rhodopsin or, in one case at least (the gwyniad2), by a rhodopsin of high λmax (520 nm). © 1973 Nature Publishing Group.