1United Graduate School of Agricultural Science, Kagoshima University, Kagoshima 890-0065, 2Faculty of Fisheries, Kagoshima University, Kagoshima 890-0056, Japan
Electroretinograms (ERGs) were recorded from the large and small pallial eyes of the scallop Amusium japonicum to determine their light perception capability. ERG recordings during the process from light to dark adaptations indicated that the light adapted eyes were completely adapted to the dark by 40 to 50 min, which was shorter than in shes. Under two consecutive light stimulations at illuminances of 2.7 lx and 50 lx, the eect of the rst stimulation on the second ERG response disappeared when the time interval between the two stimulations was longer than 20 s. Both eyes were sensitive to a wide range of spectra (433 to 700 nm) with a peak at around 470 to 520 nm, which was considered to be well adapted to the light environment of the shallow habitats of this species. ERGs were recorded under a icker light of dierent icker frequencies (0.05-10 Hz) to determine the critical fusion frequency (c), which was 1.3 to 1.5 Hz. This much lower c than found in shes was considered to be due to adaptation for the detection of slow-moving objects.