Campione Etienne, Schmid Axel
Department of Neurobiology, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090 Wien, Austria
Department of Neurobiology, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090 Wien, Austria.
J Exp Biol. 2014 Aug 1;217(Pt 15):2704-9. doi: 10.1242/jeb.103366. Epub 2014 May 6.
Cupiennius salei is a nocturnal spider with eight eyes, which undergo a remarkable circadian cycle: the rhabdomeric membrane of the photoreceptor cells is dismantled during the day and rebuilt at the beginning of the night. Such drastic changes might influence the brightness discrimination ability. We tested this hypothesis by presenting square-shaped flickering stimuli with certain luminances on stationary backgrounds with other luminances to spiders with day- or night-adapted eyes. When the spider, through its three pairs of so-called secondary eyes, perceives a visible contrast between the stimulus and the background, its principal eye muscle activity should increase. We therefore recorded this activity in vivo to assess the brightness discrimination ability of Cupiennius salei. Our results show that this spider has good brightness discrimination ability, which is significantly better with dark-adapted eyes. A Michelson contrast of 0.1 to 0.2 at night, and of 0.2 to 0.3 for day-adapted eyes, is sufficient to elicit a significant response, except below a critical value of luminance (~16 cd m(-2)), where the minimal perceivable contrast needs to be higher. In the Discussion we compare these performances with those of other animals, in particular with jumping spiders.
食鸟蛛是一种有八只眼睛的夜行性蜘蛛，其经历着显著的昼夜节律循环：光感受器细胞的视小杆膜在白天被拆解，并在夜晚开始时重新构建。如此剧烈的变化可能会影响亮度辨别能力。我们通过在具有其他亮度的静止背景上向具有适应白天或夜晚眼睛的蜘蛛呈现具有特定亮度的方形闪烁刺激来检验这一假设。当蜘蛛通过其三对所谓的副眼感知到刺激与背景之间的可见对比度时，其主眼肌肉活动应该会增加。因此，我们在活体中记录这种活动，以评估食鸟蛛的亮度辨别能力。我们的结果表明，这种蜘蛛具有良好的亮度辨别能力，暗适应眼睛的辨别能力明显更好。夜间的迈克尔逊对比度为0.1至0.2，适应白天眼睛的对比度为0.2至0.3，足以引发显著反应，但在亮度的临界值（约16 cd m(-2)）以下除外，在该临界值以下，最小可感知对比度需要更高。在讨论中，我们将这些表现与其他动物的表现进行比较，特别是与跳蛛的表现进行比较。
