Spider webs: Evolution, diversity and plasticity

The webs of spiders are the first things we notice, long before we recognise the occupant. Silk production and web building is a defining feature of all spiders, and certainly the trait they are best known for. The obvious diversity in different web types and structures has always fascinated; even Aristotle made attempts to define different web types. But it has not been until the latter half of the twentieth century that we have started to appreciate the level of diversity and plasticity in web-building behaviour, between individuals of the same species, and even within an individual from one day to the next. The recent work on silk composition and mechanics is starting to document similar levels of plasticity in response to a variety of extrinsic and intrinsic factors. We argue that that this underappreciated aspect of spider biology renders them superior models for studies investigating behavioural plasticity at the individual level. Webs, silks and decorations. The evolution of spider webs. Spider webs fulfil a number of functions of which prey capture is clearly the best recognised and studied. But webs also provide a moulting and mating platform, a retreat from predators, a place to secure egg sacs, and in some cases a diving bell (e.g. Argyroneta aquatica; Schütz et al., 2007). The reasons silk and webs evolved in the first place are still unresolved (Vollrath and Selden, 2007).