【摘要】 研究了出膜后第1～9 d的日本鳗鲡(Anguilla japonica)早期幼苗,在不同光强度下趋光性分布及视觉发育组织学特征。结果显示:在8900 lux的强光条件下,日本鳗鲡早期幼苗随着发育,表现出明显的负趋光性。到9 d时,占存活幼苗52.2%的幼苗都集中在最暗的110 lux区域;而在2300 lux的弱光条件下,表现出趋弱光性。到9 d时,占存活幼苗44.6%的幼苗都集中在25 lux区域。视网膜发育的组织学观察发现,日本鳗鲡幼苗的视网膜发育首先出现的是外界膜和内界膜,最后出现的是外丛层。幼苗的整个视网膜结构到9 d时,发育为9亚层结构。视网膜中最发达的是外核层,由3种细胞构成。发育最快的是内核层,由2种细胞构成。结果表明,与日本鳗鲡早期幼苗趋光性有关的因素包括视网膜分层、视网膜厚度、内核层细胞数等多种因素。另外,本研究还探讨了日本鳗鲡幼苗在自然界可能生存的水深和光环境。更多还原

【Abstract】 The present investigation attempted to analyze the distribution of Japanese eel(Anguilla japonica)larvae after hatching 1 d~9 d within different intension of light.The results indicated that:the larvae showed obvious negative phototaxis under the illumination of 8900 lux high light source.Apart from the 1 d larvae,which distributive number was undifferent between 300 and 110 lux region in the box,the 3 d larvae began to represent the behaviour of keeping in the darkest region within the box with their development day by day and gradually got together in the region of 110 lux.Up to 9 hatching day,52.2% survival larvae concentrated the region of 110 lux.However,the situation was different under the illumination of 2300 lux weak light source.Apart from the 1d larvae,which distributive number was undifferent between 80 and 0 lux region in the box,the larvae gradually got together the region between 40 and 10 lux with their development after 3 hatching day,not at 0 lux region which was the darkest region in the box.Up to 9 hatching day,44.6% survival larvae concentrated the region of 25 lux.Therefore,the results suggested that Japanese eel larvae avoided high light and tend towards weak light.According to the results of histological observation,inner and outer limiting membranes were the first appeared and inner plexiform cell layer was the last appeared in all sub-layers.The retinal structure of Japanese eel larvae was composed of 9 sub-layers until the 9th day after hatching.Comparing with the structure of other fish retina,there were more developed pigment cell layer and rod-cone cell layer in the retina of Japanese eel larvae,but it was conjectured that there was only one layer of rod cells in the rod and cone photoreceptor nuclei according to observing tangential section.Outer nuclear cell layer composed of 3 kind cells was the most developed layer and inner nuclear layer composed of 2 kind cells grew most rapidly in all sub-layers.Statistics analyses indicated that the factors related with larval phototaxy included number of retinal layers,retinal thick and inner nuclear cells etc together.Further analysis considered that developed pigment cell layer possessed the function of keeping larval eyes from stimulation of high light and rod cells met the need of larvae living in the condition of weak light.According to the relationship between the phototaxy and retinal development of Japanese eel larvae,this paper also discussed the light environment and depth of water that larvae lived in.更多还原