The evolution of prey wrapping behaviour in spiders

Prey wrapping behaviour, defined as the application of silk to immobilize and secure prey, is an iconic and ecologically important behaviour in spiders, yet its evolutionary origins and diversity remain poorly understood. This study provides the first comprehensive analysis of the evolution of prey wrapping behaviour across 113 spider species, representing all major extant lineages. To understand the behavioural variation and glandular origin of wrapping silks, we combined behavioural observations, high-speed videography, cryofixation experiments, and scanning electron microscopy. We identified two distinct wrapping types: silk-laying (direct spinneret contact with the prey) and hind leg wrapping (leg-mediated silk application on the prey). Contrary to prevailing assumptions that the aciniform silk glands are primarily used in prey wrapping, we demonstrate widespread involvement of multiple silk gland types, including aciniform, piriform, major ampullate, minor ampullate, and cribellar glands. Phylogenetic comparative analyses revealed that prey wrapping evolved convergently multiple times across spider lineages. Phylogenetic model comparison supported a sequential evolutionary pathway, whereby silk-laying evolved from the absence of wrapping and subsequently gave rise to the more complex hind leg wrapping form. Strong associations between hind leg wrapping and aerial web building behaviour support the hypothesis that both these behaviours evolved early and were subsequently lost repeatedly across lineages. These results establish that prey wrapping is a dynamic evolutionary trait embedded within a suite of spinning behaviours, with multiple origins, losses, and transitions among behavioural forms. By combining a robust phylogenetic comparative framework, alongside the integrative study of silk use, this work addresses a critical gap in understanding spider silk biology, linking morphological with behavioural adaptations to diverse foraging strategies.