4种岩礁性鱼类视网膜感光细胞和最小分辨角的比较

Comparison study of four species of coral-reef teleosts (Scorpaeniformes) with photoreceptor cells and the angle of minimum resolution

运用组织学方法,对铠平鲉、花斑平鲉、大泷六线鱼和斑头六线鱼的性成熟个体视网膜光感受细胞和最小分辨角进行了比较研究。结果表明:(1)大泷六线鱼和斑头六线鱼视锥细胞的排列方式为4个双锥细胞围绕一个单锥细胞构成正方形或者菱形镶嵌结构,铠平鲉和花斑平鲉的双锥细胞排列成行,单锥细胞随机分布于4个双锥细胞之间;分析认为,大泷六线鱼和斑头六线鱼视锥排列方式更复杂,单锥细胞与双锥细胞的比值(SC/DC)更高,推测其具有更好的色觉。(2)铠平鲉和花斑平鲉视柱细胞与视锥细胞的比值(R/C)大于7∶1,而大泷六线鱼和斑头六线鱼的R/C小于3∶1;推测铠平鲉和花斑平鲉更适合在夜间活动,而大泷六线鱼和斑头六线鱼属白天活动的鱼类。(3)铠平鲉、花斑平鲉、大泷六线鱼和斑头六线鱼视锥细胞密度最高处分别位于视网膜的腹-颞(V-T)区、腹区(V)、腹-颞(V-T)区和背-颞区(D-T),与各自的生活习性和摄食行为相适应。(4)4种岩礁性鱼类的成熟个体中,铠平鲉的最小分辨角最大,其次为花斑平鲉和大泷六线鱼,斑头六线鱼的最小分辨角最小。分析认为,即使是同样栖息于礁区的鱼类,其视觉特征也存在差异,这或许可以为岩礁区选择性渔具的开发提供一些有益的参考。

The photoreceptor cells and the angle of minimum resolution（AMR）for four species of coral-reef teleosts,Sebastes hubbsi, Sebastes nigricans, Hexagrammos otakii and Hexagrammos agrammus have been studied by means of common histological methods. The main results obtained are as follows： （ 1 ） Cone photoreceptors in the retinas of H. otakii and H. agrammus are arranged in a mosaic：four double cones are arranged in a square around a single central cone. The double cones of S. hubbsi and S. nigricans form highly organized rows and the single cones are distributed around four double cones occasionally. Compared with S. hubbsi and S. nigricans,the arrangement of cones for H. otakii and H. agrammus is more complex, and the ratio of single cones to double cones is greater in the retinas of H. otakii and H. agramrnus, which may indicate that H. otakii and H. agrammus have a better color vision. （2）The ratio of rod cells to cones of S. hubbsi and S. nigricans is greater than 7：1 ,but for H. otakii and H. agrammus the ratio is less than 3： 1. It is speculated that S. hubbsi and S. nigricans are nocturnal, while H. otakii and H. agrammus are diurnal. （3） The areas of greatest cone density for S. hubbsi, S. nigricans, H. otakii and H. agrammus are found in the ventral-temporal region, ventral region, ventral-temporal region and dorsal-temporal region, respectively, which is adapted to their ecology and feeding behavior. （4） For the four experimental species of fish, the AMR with S. hubbsi,S, nigricans,H, otakii and H. agrammus decrease in sequence. The preliminary analysis suggests that even in the same habitat, the visual characteristics for different species of fish vary a lot, which may provide some beneficial reference for the development of high selective fishing gear.