Coordination of Behavioral Sequences Between Individuals During Prey Capture in a Social Spider, Anelosimus eximius

The analysis of collaborative predation sequences performed by groups of 10 individuals (females) in a nonterritorial permanent-social spider, A. eximius, shows that prey-captures are organized in successive steps. Spiders begin by throwing sticky silk, which hinders the prey in the web; they then throw dry silk, which completes the immobilization of the prey. The third step is characterized by bites that paralyze the prey that will be then carried. A concordance test reveals a coordination of the individual's acts that explains the collaborative prey-capture efficiency. No individual specialization in one type of act has been shown. On the contrary, by using living preys or artificially dead vibrated preys, we show that all individuals have equipotential behaviors. Furthermore, each spider is able to adjust its behavior to the state of the prey. Individuals already involved in prey transportation can again display bites or sticky silk throwing if the prey is artificially vibrated. This mechanism, which corresponds to stimergic processes responsible for self-organized phenomena, already described in social insects, permits a coordination of individual acts without the recourse of direct communication. These results permit us to understand better how individuals coordinate their acts and lead us to support the hypothesis that the transition between solitary species and social species in spiders could have been sudden.