Meeting Abstract
Many flying insects utilize a membranous structure for flight, which is known as a “wing.” However, some spiders use silk fibers for their aerial dispersal. It is well known that spiders can disperse over hundreds of kilometers and rise several kilometers above the ground in this way. However, little remains known about the ballooning mechanisms of spiders due to the lack of quantitative data regarding spiders’ ballooning. From our observation in the field and the laboratory using a wind tunnel, we acquired knowledge of the types and physical properties of spiders’ ballooning silks, previously unknown. A crab spider weighing 20-25 mg spins 50-60 ballooning silks, which are about 200 nm thick and 3.22 m long. Silks of this size can lift large spiders (5-150 mg) into the air even with light upward air currents. In the presentation, the physical signification of these filament-like structures will be discussed in relation to the following questions: (i) Why do spiders use filament-like structures for their flight? (ii) Why do large spiders spin multiple fibers? (iii) Is there any meaning of the thickness of 200 nm?
