Gravity is very important for many organisms, including web-building spiders. Probably the best approach to study the relevance of gravity on organisms is to bring them to the International Space Station. Here, we describe the results of such an experiment where two juvenile Trichonephila clavipes (L.) (Araneae, Nephilidae) spiders were observed over a 2-month period in zero gravity and two control spiders under otherwise identical conditions on Earth. During that time, the spiders and their webs were photographed every 5 min. Under natural conditions, Trichonephila spiders build asymmetric webs with the hub near the upper edge of the web, and they always orient themselves downwards when sitting on the hub whilst waiting for prey. As these asymmetries are considered to be linked to gravity, we expected the spiders experiencing no gravity to build symmetric webs and to show a random orientation when sitting on the hub. We found that most, but not all, webs built in zero gravity were indeed quite symmetric. Closer analysis revealed that webs built when the lights were on were more asymmetric (with the hub near the lights) than webs built when the lights were off. In addition, spiders showed a random orientation when the lights were off but faced away from the lights when they were on. We conclude that in the absence of gravity, the direction of light can serve as an orientation guide for spiders during web building and when waiting for prey on the hub.

重力对于许多生物非常重要，包括蜘蛛网。研究重力与生物的相关性的最佳方法可能是将它们带到国际空间站。在这里，我们描述了这样一个实验的结果，其中在零重力的情况下在两个月内观察到了两只幼年的网毛棘金线虫（L。）（蜘蛛属，Nephilidae）蜘蛛，在其他条件相同的情况下，观察到了两只对照蜘蛛。在此期间，每5分钟拍摄一次蜘蛛及其网。在自然条件下，赤眼蜂蜘蛛会在轮毂靠近网的上边缘的位置建造不对称的网，当它们坐在轮毂上等待猎物时，它们总是将自己向下定向。由于这些不对称性被认为与重力有关，因此我们希望没有重力的蜘蛛会建立对称的腹板，并且坐在轮毂上时会显示随机的方向。我们发现，大多数但不是全部以零重力建造的腹板确实相当对称。进一步的分析显示，开灯时建造的网比关灯时建造的网更不对称（轮毂靠近灯）。另外，蜘蛛在灯光关闭时表现出随机的方向，而在灯光打开时却背对着灯光。我们得出结论，在没有重力的情况下，