Department of Biology, University of Florence, Via Romana 17, 50125, Florence, Italy.
Department of Biology, School of Medicine, Hamamatsu University, 1-20-1, Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2020 Sep;206(5):711-723. doi: 10.1007/s00359-020-01432-8. Epub 2020 Jun 19.
We investigated the eye regionalization in Talitrus saltator by morphological, electrophysiological and behavioural experiments. Each ommatidium possesses five radially arranged retinular cells producing a square fused rhabdom by R1-R4 cells; the smaller R5 exists between R1 and R4. The size of R5 rhabdomere is larger in the dorsal part and becomes smaller in the median and ventral parts of the eye. Spectral-sensitivity by electroretinograms were recorded from dorsal or ventral parts of the eye. The dorsal part possesses maxima at green and UV-blue region. The main response region in the ventral part is only from UV (390 nm) to blue (430 nm) decreasing at longer wavelengths. To evaluate the sandhoppers' celestial orientation, their eyes were painted black either in the dorsal or ventral part, under the natural sky or a blue filter with or without the vision of the sun. Sandhoppers with the dorsal region of the eyes painted and tested under the screened sun were more dispersed and their directions varied more than in other groups of individuals. Sandhoppers with this area of the eye obscured display considerable difficulties to head in a specific direction. This work suggests the existence of regional specializations in the eye of T. saltator.
我们通过形态学、电生理学和行为学实验研究了潮间带沙蚤的眼部区域化。每个小眼具有五个径向排列的光感受细胞，通过 R1-R4 细胞产生方形融合的光感受器；较小的 R5 存在于 R1 和 R4 之间。R5 光感受器的大小在眼睛的背部较大，在中部和腹部变小。从眼睛的背部或腹部记录视网膜电图的光谱敏感性。背部在绿光和 UV-蓝光区具有最大值。在腹部的主要反应区域仅从 UV（390nm）到蓝（430nm），在较长波长处减少。为了评估沙蚤的天体定向，它们的眼睛要么在背部要么在腹部被涂成黑色，在自然天空或蓝色滤光片下，有或没有太阳的视觉。在遮蔽的阳光下对眼睛背部进行涂漆和测试的沙蚤分布更加分散，它们的方向比其他个体组变化更大。眼睛这一区域被遮挡的沙蚤显示出难以朝特定方向前进的明显困难。这项工作表明，潮间带沙蚤的眼睛存在区域特化。
