Dragline Attachment Pattern in the Neotropical Social Spider <Emphasis Type="Italic">Anelosimus eximius</Emphasis> (Araneae: Theridiidae)

The regularity of spiders orb webs has been considered a fascinating natural wonder by generations of naturalists. Although the majority of spider species build irregular three-dimensional networks, those who have evolved the twodimensional spiral snare have drawn most of the attention (Vollrath, 1988). Even studies conducted on irregular webs are often explicitly devoted to the search of similarities with orb webs, resulting from behavioral preadaptations to this specific design (Eberhard, 1987, 1992). So the question of the distance between attachment points in an environment that does not feature intrinsinc regulating properties, like a three-dimensional web or vegetal structure, remains widely open. In the overall context of swarming in the cooperative spider Anelosimus eximius (Furey et al, in preparation), our focus was on amplification mechanisms involved in group cohesion and coordination of several individuals' activities. From these observations, it appears that dragline attachment pattern has a direct influence on network design, and consequently on the population transfer's dynamics, which is confirmed by theoretical projections about the efficiency of silk-mediated exploratory recruitment (Saffre et al, 1997, in press).