BLACK widow spiders vary their webs to suit their purpose. A hungry spider spins a deadlier web, while a full one builds a fortress.
Spiders that were fed daily with crickets spun tangled masses of non-sticky silk, Jacquelyn Zevenbergen and Todd Blackledge at the University of Akron, Ohio, found. But similar-size spiders that had been starved for a week tended to spin sheets of silk connected to the ground by taut, sticky strands. When an insect blunders into these strands, they detach from the ground and spring upwards, suspending the prey in mid-air.
The sheet-like webs are better at transmitting the vibrations of passing prey and also make it easier for the spider to manoeuvre. The researchers found that all spiders, regardless of their condition, caught more prey more quickly and efficiently when they placed them on the webs spun by hungry individuals.
Blackledge suggests that sated spiders opt to spin tangled, non-sticky webs because they provide better protection from predators. This type of purposeful alteration to web design is unique to black widows. “Their webs aren’t simply more or less of the same thing,” he says. “They are adding and deleting architectural features that have specific functions.”