Intricate web patterns help spiders pinpoint their captured prey

By Stephen Beech

Spider web “decorations” may help arachnids to pinpoint the location of their captured prey, suggests a study.

The “extra touches” to intricate webs - known as stabilimenta - enable the eight-legged hunters to find their next meal, according to the findings.

An international research team, led by Swedish scientists, say the discovery could inspire innovation in spider web-mimicking synthetic materials

Many spider species build spiral wheel-shaped webs - known as orb webs - to capture flying prey, and many can incorporate stabilimenta into the web structure.

The “decorations” may look like zig-zagging threads spanning the gap between two adjacent “spokes,” or threads arranged in a circular “platform” around the web centre.

The exact purpose of stabilimenta is unclear, with proposed functions include water collection, body temperature regulation, and balancing insect attraction with deterrence of predatory wasps or birds.

Another possibility is that stabilimenta aid spiders by influencing the propagation of web vibrations triggered by the impact of captured prey.

But, until now, no studies had explored the idea.

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Dr. Gabriele Greco, of the Swedish University of Agricultural Sciences in Uppsala, and his colleagues observed different stabilimentum geometries constructed by wasp spiders.

Based on the structures, the researchers then ran numerical simulations to explore how stabilimenta affect prey impact vibrations.

Dr. Greco said: "In the simulations, the presence or absence of stabilimenta affected web vibrations differently, depending on the angle of the waves generated by prey impact.

"For waves generated at angles perpendicular to the web surface or perpendicular to the threads spiralling out from the web centre, stabilimenta caused negligible delays in wave propagation.

"However, for waves generated in the same direction as the spiral threads, vibrations in webs with stabilimenta propagated to a greater number of potential detection points across the web - where a spider might sense them - than in webs without stabilimenta.

"This suggests that stabilimenta may boost a spider’s ability to pinpoint the location of prey caught in its web."

While the findings deepen understanding of stabilimenta, the researchers noted that their real-world impact on prey localisation may be limited, with other functions having greater effects.

But they say the study, published in the journal PLOS One, could inform the design of web-inspired synthetic materials with finely tuned wave-propagation abilities.

Dr. Greco added: “This study reveals that the decorative stabilimentum in wasp spiders webs is more than just ornament, for it subtly changes how certain vibrations travel through the web.

"By combining field observations and simulations, the work discusses the mechanical role for stabilimenta and inspires designs for bio-inspired materials with tuneable elastic properties.”