Lakin R C, Jinks R N, Battelle B A, Herzog E D, Kass L, Renninger G H, Chamberlain S C
Department of Bioengineering and Neuroscience, Syracuse University, New York 13244, USA.
J Comp Neurol. 1997 Sep 8;385(4):503-14.
Exploration of deep-sea hydrothermal vents over the past quarter century has revealed that they support unique and diverse biota. Despite the harsh nature of the environment, vents along the Mid-Atlantic Ridge are dominated by large masses of highly motile Bresiliid shrimp. Until 1989, when it was discovered that the vent shrimp Rimicaris exoculata possesses a hypertrophied dorsal eye, many believed that animals populating hydrothermal vents were blind. Chorocaris chacei (originally designated Rimicaris chacei) is a Bresiliid shrimp found at hydrothermal vent fields along the Mid-Atlantic Ridge. Like R. exoculata, C. chacei has a hypertrophied retina that appears to be specialized to detect the very small amount of light emitted from the orifices of black smoker hydrothermal vent chimneys. C. chacei lacks the sophisticated compound eyes common to other decapod crustaceans. Instead, it has a smooth cornea, with no dioptric apparatus, apposed by a tightly packed, massive array of photosensitive membrane. Photoreceptors in the C. chacei retina are segmented into a hypertrophied region that contains the photosensitive membrane and an atrophied cell body that is roughly ten times smaller in volume than the photosensitive segment. The microvillar photosensitive membrane is consistent in structure and ultrastructure with the rhabdoms of decapod and other invertebrate retinas. However, the volume density of photosensitive membrane (> or =60%) exceeds that typically observed in invertebrate retinas. The reflecting pigment cells commonly found in decapod retinas are represented in the form of a matrix of white diffusing cells that exhibit Tyndall scattering and form an axial sheath around the photoreceptors. All photoreceptor screening pigment granules and screening pigment cells are restricted to the region below the photoreceptor nuclei and are thereby removed from the path of incident light. No ultrastructural evidence of rhythmic cycling of photosensitive membrane was observed. The morphological adaptations observed in the C. chacei retina suggest that it is a high-sensitivity photodetector that is of functional significance to the animal.
在过去的四分之一世纪里，对深海热液喷口的探索揭示了它们支撑着独特而多样的生物群落。尽管环境恶劣，但大西洋中脊的喷口却被大量高度活跃的巴西列虾所主导。直到1989年，人们发现喷口虾“外眼柱虾”（Rimicaris exoculata）拥有一个肥大的背眼，许多人才相信生活在热液喷口的动物是盲的。“查氏柱虾”（Chorocaris chacei，最初被命名为“查氏外眼柱虾”Rimicaris chacei）是在大西洋中脊热液喷口区发现的一种巴西列虾。与外眼柱虾一样，查氏柱虾也有一个肥大的视网膜，似乎专门用于探测黑烟囱热液喷口烟囱口发出的极少量光线。查氏柱虾没有其他十足目甲壳类动物常见的复杂复眼。相反，它有一个光滑的角膜，没有屈光装置，旁边是紧密排列的大量光敏膜。查氏柱虾视网膜中的光感受器被分为一个包含光敏膜的肥大区域和一个萎缩细胞体，萎缩细胞体的体积大约比光敏部分小十倍。微绒毛光敏膜在结构和超微结构上与十足目和其他无脊椎动物视网膜的视杆一致。然而，光敏膜的体积密度（≥60%）超过了无脊椎动物视网膜中通常观察到的密度。十足目视网膜中常见的反射色素细胞以白色散射细胞矩阵的形式存在，这些细胞表现出廷德尔散射，并在光感受器周围形成一个轴向鞘。所有光感受器筛选色素颗粒和筛选色素细胞都局限于光感受器细胞核下方的区域，从而被排除在入射光的路径之外。未观察到光敏膜有节律循环的超微结构证据。在查氏柱虾视网膜中观察到的形态适应表明，它是一种对动物具有功能意义的高灵敏度光探测器。
