Creative problem solving in a jumping spider

Behavioural innovation, a key indicator of advanced cognition, has been well-documented across animal taxa and manifests as creative problem-solving. Typical innovators such as apes and corvids can spontaneously solve complex, multi-step tasks individually without prior training. Innovative behaviours in arthropods—honeybees, bumblebees and ants—are probably underestimated, because their innovative behaviours are often considered products of associative learning, group-level processes, or one-step problem-solving. Here, we challenge this view by demonstrating spontaneous, individual-level innovation in nest construction by the social living jumping spider Toxeus maxillosus (formerly Toxeus magnus), without prior training or external demonstration. Under four challenging lab conditions, T. maxillosus females exhibited the core components of typical innovative behaviours: environmental exploration, behavioural flexibility, insight and action planning. Furthermore, in a vertical string-pulling task (a benchmark test of animal innovation), half of the spiders pulled an out-of-reach sponge upward and incorporated it into the inner wall of the device, thereby creating a suitable microstructure for nest construction. These behaviours demonstrate multi-step, goal-directed manipulation. Our findings suggest that arthropods are capable of individual-level, spontaneous innovation involving planning and multi-step sequences, akin to that observed in typical innovators. We propose that the social lifestyle centered on prolonged maternal care—a trait shared by T. maxillosus and many vertebrate innovators—rather than large brain size or long lifespan, may be a critical evolutionary driver of such cognitive complexity. This study challenges the vertebrate-centric view of typical innovation and provides a new framework for understanding the evolution of cognition across phylogenetic scales.