Visual mechanisms of hunting behaviour inTrite planiceps,a jumping spider (Araneae: Salticidae)

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Abstract
Jumping spiders rely on visual stimuli when catching their prey. Each of the hunting actions employed is mediated by one or more of the three pairs of eyes responsible for this behaviour. No function has yet been demonstrated for the tiny fourth pair of eyes. Two distinct post-detection hunting strategies are used; one enables spiders to catch their prey on the run, and the other controls the capture of stationary prey. Exclusive components of each of these strategies are (i) chasing, which is a function of the anterior-lateral eyes, and (ii) stalking, which is a function of the anterior-median eyes; collaborative visual mechanisms result in a smooth transition from one mode of behaviour to another. In addition, both strategies employ common behavioural elements that exploit specialised properties of the four anterior eyes; successful prey capture is a measure of their physiological and behavioural synchronisation. ‘Short jumps’ towards targets moving at an angular velocity of more than 15°/s are mediated by the anterior-lateral eyes when the anterior-median eyes are covered. Since a significant negative correlation (P<0.005) is shown between these short jump distances and target velocity, the anterior-lateral eyes must process information relative to these variables. Unilateral occlusion of an adjacent pair of anterior eyes (an anterior-lateral and an anterior-median) demonstrates that visual information transmitted by the sighted pair controls the specialised hunting postures on that particular side of the body. However, similarly blinded males exhibit bilateral leg-raising responses to each other and to females. Hence, the mechanisms of visual control in agonistic and courtship behaviour probably differ from those that direct prey-catching sequences.