Flexible foraging and mating behaviours in an orb weaver

The evolution of the orb web was associated with a major radiation in spider diversity. Orb webs evolved for prey capture, and they also play important roles in courtship and mating. However, the construction and use of orb webs has associated costs, and the modification and loss of orb webs have evolved multiple times. While variation between species is evident, such as reductions or loss of the orb web for foraging, this kind of variation is rarely detailed within species. Here, I describe laboratory observations of foraging and mating without an orb web in a typical orb-weaving spider, the Australian garden orb weaver (hortophora biapicata). The behavioural range observed here shows the natural variation in these traits, on which selection might act to drive the reduction or loss of orb webs. Further investigation of these rare and unusual behaviours can help us understand the function and origin of important traits associated with the orb web, including both its construction and use, and how these traits can change over evolutionary time.