Steinhoff Philip O M, Harzsch Steffen, Uhl Gabriele
Zoological Institute and Museum, General and Systematic Zoology, University of Greifswald, Greifswald, Germany.
Zoological Institute and Museum, Cytology and Evolutionary Biology, University of Greifswald, Greifswald, Germany.
J Comp Neurol. 2023 Nov 10;532(2):e25554. doi: 10.1002/cne.25554.
Spiders (Araneae) include cursorial species that stalk their prey and more stationary species that use webs for prey capture. While many cursorial hunting spiders rely on visual cues, web-building spiders use vibratory cues (mechanosensation) for prey capture. We predicted that the differences in primary sensory input between the species are mirrored by differences in the morphology/architecture of the central nervous system (CNS). Here, we investigated the CNS anatomy of four spider species, two cursorial hunters Pardosa amentata (Lycosidae) and Marpissa muscosa (Salticidae), and two web-building hunters Argiope bruennichi (Araneidae) and Parasteatoda tepidariorum (Theridiidae). Their CNS was analyzed using Bodian silver impregnations, immunohistochemistry, and microCT analysis. We found that there are major differences between species in the secondary eye pathway of the brain that pertain to first-order, second-order, and higher order brain centers (mushroom bodies [MB]). While P. amentata and M. muscosa have prominent visual neuropils and MB, these are much reduced in the two web-building species. Argiope bruennichi lacks second-order visual neuropils but has specialized photoreceptors that project into two distinct visual neuropils, and P. tepidariorum lacks MB, suggesting that motion vision might be absent in this species. Interestingly, the differences in the ventral nerve cord are much less pronounced, but the web-building spiders have proportionally larger leg neuropils than the cursorial spiders. Our findings suggest that the importance of visual information is much reduced in web-building spiders, compared to cursorial spiders, while processing of mechanosensory information requires the same major circuits in both web-building and cursorial hunting spiders.
蜘蛛(蜘蛛目)包括四处游走追捕猎物的种类以及更多利用蛛网捕获猎物的相对静止的种类。虽然许多游走捕猎型蜘蛛依靠视觉线索,但织网型蜘蛛利用振动线索(机械感觉)来捕获猎物。我们预测,不同种类蜘蛛在初级感觉输入上的差异会反映在中枢神经系统(CNS)的形态/结构差异上。在此,我们研究了四种蜘蛛的中枢神经系统解剖结构,其中两种是游走捕猎者,即豹蛛(狼蛛科)和蝇虎(跳蛛科),另外两种是织网捕猎者,即横纹金蛛(园蛛科)和温和肥腹蛛(球蛛科)。我们使用博迪安银浸染法、免疫组织化学和显微CT分析对它们的中枢神经系统进行了分析。我们发现,不同种类蜘蛛在大脑的次级眼通路方面存在主要差异,这些差异与一级、二级及更高级别的脑区(蘑菇体[MB])有关。虽然豹蛛和蝇虎具有明显的视觉神经纤维网和蘑菇体,但在这两种织网型蜘蛛中,这些结构大为减少。横纹金蛛缺乏二级视觉神经纤维网,但有专门的光感受器投射到两个不同的视觉神经纤维网中,而温和肥腹蛛缺乏蘑菇体,这表明该物种可能缺乏运动视觉。有趣的是,腹神经索的差异不太明显,但织网型蜘蛛的腿部神经纤维网比游走型蜘蛛的比例更大。我们的研究结果表明,与游走型蜘蛛相比,视觉信息在织网型蜘蛛中的重要性大大降低,而在织网捕猎型蜘蛛和游走捕猎型蜘蛛中,机械感觉信息的处理都需要相同的主要神经回路。