A single drawing from a 94-year-old scientific paper has sparked renewed intrigue in the unique feeding method of a spider species known as the feather-legged lace weaver (Uloborus plumipes). This unusual predation technique involves wrapping a piece of prey, like a fruit fly, in silk and then excreting potent toxins over the meal. Evolutionary biologist Giulia Zancolli from the University of Lausanne stumbled upon this information while reviewing another lab’s paper, leading her to trace references back to a drawing in a 1931 publication. The unexpected revelation of this feeding method highlights how historical research can inform and inspire modern scientific inquiries.
Zancolli and her team meticulously studied the feather-legged lace weaver by collecting specimens from plant shops and landscaping nurseries, where the spiders can blend into their environment due to their delicate bodies. These spiders often fold their front legs under, making them resemble dry leaves, which serves as an effective camouflage. Researchers noted that the spiders are adept at wrapping their prey in silk, sometimes employing hundreds of meters of silk to ensnare a single meal. This meticulous wrapping prepares the prey for the next step in the unique feeding process.
Most spider species utilize venom to subdue their prey through an injection method; however, the feather-legged lace weaver diverges from this norm. Detailed examinations of U. plumipes revealed muscle formations in their heads where venom glands are typically found. Instead of injecting venom, the lace weaver’s fangs lack ducts for delivering toxins. Researchers discovered that instead of venom, the spider’s midgut contains genes associated with producing potent toxins, suggesting an evolutionary adaptation to their unique foraging technique.
Unlike many spiders that rely on venom for immobilization, the feather-legged lace weaver’s regurgitated toxins, particularly those from its midgut, were found to be equally lethal. In experiments, these toxins were effective against fruit flies, showcasing their ability to kill prey efficiently without the traditional venom injection method. The spiders display notable caution in their feeding strategy, generously applying their excreted toxins over their silk-wrapped meals rather than applying minimal amounts.
To clearly illustrate the differences between the feather-legged lace weaver’s fangs and those of traditional venomous spiders, the research included close-up images contrasting these adaptations. The lace weaver’s structure lacks the necessary plumbing for venom delivery, thereby confirming the unique feeding technique. In the images, one can see where typical spider fangs, equipped with ducts, effectively deliver venom, while the lace weaver’s fangs remain devoid of such features.
As Zancolli’s research underscores the diversity of feeding behaviors in the spider world, it opens up further questions regarding the evolutionary drivers behind such adaptations. Understanding the feather-legged lace weaver’s method not only sheds light on its specific ecological niche but also contributes to broader knowledge about predation strategies among arachnids. The revival of interest in this unique spider demonstrates the continuous interplay between historical and contemporary research, offering new avenues for exploration in the field of evolutionary biology.
