Web Inception: Small Australia Spiders Construct Orb Webs in the Aerial Webs of Larger Hosts

ABSTRACT Aerial webs are an extended phenotype that allow spiders to filter prey from the air. These webs also provide novel habitat that heterospecifics can exploit by providing scaffolding for web building, and thus access to air spaces that may not otherwise be attainable. In this study, we report on smaller orb‐weaving spiders constructing aerial webs within those of larger spiders in Australia. Across Kooragang Island, New South Wales, Australia, we observed the orb webs of two different species, Larinia sp. and Tetragnatha sp., on the outskirts of larger host webs. These web associations showcase how the extended phenotype of one species can be exploited by another species for aerial web construction, given that the invading spiders are using the anchoring threads of their host to build their aerial web frameworks. The benefits of this behaviour may include a reduction in the amount of silk and time required to construct aerial webs, as well as gaining access to prey routes that improve foraging success. This does not appear to be associated with a risk of predation by the web hosts, who may tolerate the presence of the invader's web given that it does not impede prey capture and as there may be some degree of resource partitioning, or even benefits from hosting the invaders if they attract additional prey. It remains to be determined how these smaller spiders are able to detect the presence of larger webs to coalesce their own webs to and whether it is a chance association that is subsequently exploited or if web‐in‐web construction is encouraged by certain environmental conditions.