O'Neill P J, Jinks R N, Herzog E D, Battelle B A, Kass L, Renninger G H, Chamberlain S C
Department of Bioengineering and Neuroscience, Syracuse University, NY 13244-5290, USA.
Vis Neurosci. 1995 Sep-Oct;12(5):861-75. doi: 10.1017/s0952523800009421.
The bresiliid shrimp, Rimicaris exoculata, lives in large masses on the sides of hydrothermal vent chimneys at two sites on the Mid-Atlantic Ridge. Although essentially no daylight penetrates to depths of 3500 m, very dim light is emitted from the hydrothermal vents themselves. To exploit this light, R. exoculata has evolved a modified compound eye on its dorsal surface that occupies about 0.5% of the animal's body volume. The eye's morphology suggests that it is extremely sensitive to light. The cornea of the dorsal eye is smooth with no dioptric apparatus. The retina consists of two wing-shaped lobes that are fused across the midline anteriorly. The rhabdomeral segments of the 7000 ommatidia form a compact layer of photosensitive membrane with an entrance aperture of more than 26 mm2. Within this layer, the volume density of rhabdom is more than 70%. Below the rhabdomeral segments, a thick layer of white diffusing cells scatters light upward into the photoreceptors. The arhabdomeral segments of the five to seven photoreceptors of each ommatidium are mere strands of cytoplasm that expand to accommodate the photoreceptor nuclei. The rhabdom is comprised of well-organized arrays of microvilli, each with a cytoskeletal core. The rhabdomeral segment cytoplasm contains mitochondria, but little else. The perikaryon contains a band of mitochondria, but has only small amounts of endoplasmic reticulum. There is no ultrastructural indication of photosensitive membrane cycling in these photoreceptors. Vestigial screening pigment cells and screening pigment granules within the photoreceptors are both restricted to the inner surface of the layer of the white diffusing cells. Below the retina, photoreceptor axons converge in a fanshaped array to enter the dorsal surface of the brain. The eye's size and structure are consistent with a role for vision in shrimp living at abyssal hydrothermal vents.
巴西异腕虾（Rimicaris exoculata）大量栖息在大西洋中脊两个区域的热液喷口烟囱壁上。尽管在3500米深处基本上没有日光能够穿透，但热液喷口本身会发出非常微弱的光。为了利用这种光，巴西异腕虾在其背表面进化出了一个经过改良的复眼，其体积约占动物身体体积的0.5%。眼睛的形态表明它对光极其敏感。背眼的角膜光滑，没有屈光装置。视网膜由两个翼状叶组成，它们在前方中线处融合。7000个小眼的视杆节段形成了一层紧密的光敏膜，其入射孔径超过26平方毫米。在这一层内，视杆的体积密度超过70%。在视杆节段下方，一层厚厚的白色散射细胞将光向上散射到光感受器中。每个小眼的五到七个光感受器的非视杆节段仅仅是细胞质的细丝，会扩展以容纳光感受器细胞核。视杆由排列有序的微绒毛阵列组成，每个微绒毛都有一个细胞骨架核心。视杆节段的细胞质中含有线粒体，但其他成分很少。细胞周质含有一排线粒体，但只有少量内质网。这些光感受器中没有光敏膜循环的超微结构迹象。残余的屏蔽色素细胞和光感受器内的屏蔽色素颗粒都局限于白色散射细胞层的内表面。在视网膜下方，光感受器轴突以扇形阵列汇聚，进入大脑的背表面。眼睛的大小和结构与生活在深海热液喷口的虾利用视觉的功能相一致。
