Web tuning of an orb-web spider, Octonoba sybotides, regulates prey-catching behaviour

An uloborid spider (Oclonoba sybotides constructs two types of web which are distinguished by linear or spiral stabilimenta. Food-deprived spiders tend to construct webs with spiral stabilimenta and food-satiated spiders tend to construct webs with linear stabilimenta. I experimentally examined the influence of web type on the speed of a spider's response to small and large flies. The results indicated that web type rather than the spiders' energetic condition influences the response speed to small or large Drosophila flies. I also examined whether thread tension affects the response speed of spiders by increasing the tension of the radial threads. The results showed that spiders on an expanded web responded to small prey as quickly as spiders on webs with spiral stabilimenta. The tension of the radial threads may be regulated by the degree of distortion of the radial threads at the hub. O. sybotides seems to construct orb webs which induce different responses for smaller, less-profitable prey according to its energetic state. The spider appears to increase the tension of the radial threads so that it can sense smaller prey better when hungry.