Pupil response was studied photographically in four shark species: Ginglymostoma cirratum, Carcharhinus milberti, Negaprion brevirostris, and Galeocerdo cuvieri. Constriction and dilation take place in significantly less than 1 min in three of the four species. These rates suggest that pupil control...
ACh and NE activity during fluctuations in pupil size During stillness both cholinergic and noradrenergic axonal activity was elevated while the pupil was dilating, and was reduced during constriction. NE activity levels were larger and shorter latency than ACh preceding the peak of a dilation (Fig....