from Myrmica rubra ant colonies. These ants are predators and the pheromones they release for communication have a notable deterrent effect on these spider species. Web types There is no consistent relationship between the classification of spiders and the types of web they build: species in the same genus may build very similar or significantly different webs. Nor is there much correspondence between spiders' classification and the chemical composition of their silks. Convergent evolution in web construction, in other words use of similar techniques by remotely related species, is rampant. Orb web designs and the spinning behaviors that produce them are the best understood. The basic radial-then-spiral sequence visible in orb webs and the sense of direction required to build them may have been inherited from the common ancestors of most spider groups. However, the majority of spiders build non-orb webs. It used to be thought that the sticky orb web was an evolutionary innovation resulting in the diversification of the Orbiculariae. Now, however, it appears that non-orb spiders are a subgroup that evolved from orb-web spiders, and non-orb spiders have over 40% more species and are four times as abundant as orb-web spiders. Their greater success may be because sphecid wasps, which are often the dominant predators of spiders, much prefer to attack spiders that have flat webs. Orb About half the potential prey that hit orb webs escape. A web has to perform three functions: intercepting the prey (intersection), absorbing its momentum without breaking (stopping), and trapping the prey by entangling it or sticking to it (retention). No single design is best for all prey. For example: wider spacing of lines will increase the web's area and hence its ability to intercept prey, but reduce its stopping power and retention; closer spacing, larger sticky droplets and thicker lines would improve retention, but would make it easier for potential prey to see and avoid the web, at least during the day. However, there are no consistent differences between orb webs built for use during the day and those built for use at night. In fact, there is no simple relationship between orb web design features and the prey they capture, as each orb-weaving species takes a wide range of prey. The hubs of orb webs, where the spiders lurk, are usually above the center, as the spiders can move downwards faster than upwards. If there is an obvious direction