鳜鱼视觉特性及其对捕食习性适应的研究Ⅰ．视网膜电图光谱敏感性和适应特性

采用电生理方法研究了夜行性凶猛鱼类鳜鱼视网膜电图的一般特性、光谱敏感性和适应特性。顷鱼的视网膜电图不显示典型的混合型视网膜特征。明视和暗视视网膜电图的光谱敏感曲线形状基本相同，峰值都在５３０ｎｍ处，没有出现Ｐｕｒｋｉｎｊｅ氏位移。明适应曲线仅出现下降型变化，暗适应过程异常缓慢。鳜鱼的视网膜仅存在单一的光感受系统，即暗视系统，不可能形成色觉。但级鱼视网膜具有很高的光敏感性，适于弱光视觉。

VISUAL CHARACTERISTICS OFMANDARIN FISH (SINIPERCA CHUATSI)IN RELATION TO ITS FEEDING HABIT:I. PHOTO-SENSITIVITY AND SPECTRALSENSITIVITY OF ELECTRORETINOGRAM

The electroretinogram (ERG) of intact eyes were recorded to study the retinalphoto-sensitivity and spectral sensitivity of a nocturnal predator, the mandarin fish,Siniperca chuatsi. The ERG forms of the fish are almost the same at scotopia and photopiaexcept that a small d-wave was observed at photopia when evoked by the strongest stimuluslight. The threshold value in dark-adapted state is 1,000 times smaller than that inlight-adapted state.The scotopic and photopic spectral sensitivity curves are identical in shape, with theirpeaks being located at a wavelength near 530nm. The Purkinje phenomenon was not ob-served in this fish.At both weak and intense background illuminations, only can the decreased type oflight-adaptation curves be seen in the change of b-wave sensitivity .When retina is previous-ly light-adapted by an intense background illumination,the threshold changes slowly andcannot restore the threshold of fully dark-adapted retina after three hours.There are noshoulders or turnings recorded in dark-adaptation curves of the fish.Since only one receptor system is present in the retina of the mandarin fish,we can thussuggest that this fish is of colour blindness,and it improves its photo-sensitivity by theabandonment of colour vision,so as to enable itself to recognize preys in a very dim light.