Kunz Y W, Ni Shuilleabhain M, Callaghan E
Exp Biol. 1985;43(3):161-78.
The benthic Trachinus vipera occurs to a depth of 50 m and migrates inshore during the summer. It lies buried in the sand with the top of its head exposed. The benthic habitat and predatory behaviour, tuned to function in twilight, are reflected in the structure and ultrastructure of the eye. The eye is well camouflaged by an iridescent cornea and a differentially coloured spectacle. The spontaneous eye movements are either coordinated, for binocularity, or independent, for monocular vision. The latter is aided by the reduction of the blind spot to a thin streak. Consequently the optic nerve is flattened. When leaving the eyeball it becomes folded, which may allow for lengthening. The cones of the duplex retina are arranged in a square mosaic, with a central single cone and identical twin cones. The square mosaic is stabilized by an intricate framework of so-called "fins", and the twin cones do not "twist" into a row pattern in the dark as observed in the diurnal guppy. The twin cones do not extend sclerally in the dark, while the single cones, rods and pigment epithelial processes undergo retinomotor movements. Regional differences are observed: The sensitivity of the dorsal retina is enhanced by a great number of rods, bundled as in deep-sea fish. The lipid granules in the dorsal pigment epithelium may act as a tapetum lucidum, reflecting light back through the retina. A cluster of triple cones in the dorso-temporal region may represent a site for increased sensitivity and/or acute vision. An unusual inclusion body, with a dense core similar to a lipid droplet, and surrounded by membranes, is observed in the dorsal pigment epithelium. The membranes are seen to be continuous with the smooth endoplasmic reticulum, nuclear membrane and myeloid bodies. This body changes diurnally and may be a type of phagosome.
底栖的毒鲉可生活在水深达50米的区域，并在夏季向近海洄游。它埋于沙中，头部露出。其底栖栖息地和捕食行为适应于黄昏时分的活动，这在眼睛的结构和超微结构中有所体现。眼睛被一层虹彩角膜和颜色各异的眼膜很好地伪装起来。眼睛的自发运动要么是协调的（用于双眼视觉），要么是独立的（用于单眼视觉）。后者因盲点缩小为一条细缝而得到辅助。因此，视神经变扁平。当离开眼球时，它会折叠起来，这可能有助于其延长。双重复合视网膜的视锥细胞呈方形镶嵌排列，中央有一个单视锥细胞和一对相同的双视锥细胞。方形镶嵌结构由一个复杂的所谓“鳍”框架稳定，并且双视锥细胞在黑暗中不会像昼行性孔雀鱼那样“扭曲”成一排。双视锥细胞在黑暗中不会向巩膜方向延伸，而单视锥细胞、视杆细胞和色素上皮细胞的突起会进行视网膜运动。存在区域差异：背侧视网膜的敏感性因大量视杆细胞而增强，这些视杆细胞像深海鱼类那样成束排列。背侧色素上皮中的脂质颗粒可能起到反光层的作用，将光线反射回穿过视网膜。背颞区域的一簇三联视锥细胞可能代表着一个敏感性增强和/或具有敏锐视觉的部位。在背侧色素上皮中观察到一种不寻常的包涵体，其有一个类似于脂质小滴的致密核心，并被膜包围。这些膜被发现与滑面内质网、核膜和髓样体相连。这个包涵体每天都会变化，可能是一种吞噬体。
