Spindle knots on spider silk are regarded as the key property that enables spider webs to collect moisture. Previous authors have stated that liquids will always move to the widest part of the spindle knot. However, new theoretical and experimental results reported here show that this is not necessarily correct. Using analytical theoretical results along with numerical simulation and carefully designed experiments, the behavior of liquid drops on spindle knots has been analyzed. It was found that spindle knots can drive the drop to the widest region, as reported by previous authors, or to the narrowest region. In addition, under certain conditions, the drop may not move at all. The conditions for moving the drops is presented.
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