In an experimental study, mechanisms by which cooperative prey transport is achieved in social spiders were clarified. Factors that could influence the number of individuals that participate in prey transport (prey mass, length and vibration) were investigated. Results show that two factors are fundamental: the vibrations and the prey length. Prey mass did not seem to influence spiders' participation. Thus, the single fact that individuals respond locally to environmental stimuli (intensity of vibration, available site on the prey) explains how spiders cooperate and efficiently capture a wide range of prey types without complex communication systems.