Optical cues used in predation by jumping spiders, Phidippus audax (Araneae, Salticidae)

Jumping spiders are known to rely on visual information when making predatory decisions, but the relative roles of global and local motion, shape and interior spatial detail in eliciting attack remain poorly resolved. We manipulated videos of crickets and presented jumping spiders, Phidippus audax, with choice tests. Consistent with previous studies, spiders more often approached videos depicting moving prey versus motionless prey. Spiders attended to local motion characteristics, preferring videos of natural cricket motion over videos of a snapshot of a cricket that moved across the screen with the same start-and-stop global motion pattern as the natural cricket. However, spiders showed no evidence of preference between moving images that differed in shape and interior spatial detail: a cricket snapshot and a rectangle of the same size and colour. These results indicate that spiders either cannot detect differences between the stimuli, or can detect differences but show no preference. To distinguish between these possibilities, we used an aversive conditioning protocol. Conditioning was effective, as we could train spiders to choose a moving snapshot over a natural cricket. However, we were unable to induce discrimination between cricket snapshots and rectangles, suggesting that spiders were unable to distinguish these images even when motivated to do so. There was no significant difference in the spiders' propensity to choose cricket videos with natural stop-and-start motion versus those without pauses, so we found no evidence that the commonly observed pausing behaviour of walking prey influences the propensity of spiders to attack. Taken together, our results support the hypothesis that movement is more important than image shape for predatory decisions of this jumping spider.