Prey-dependent feeding behavior in a kelp-forest mesopredator, the California two-spot octopus

Abstract

Predators have evolved a diverse behavioral repertoire to capture and handle prey. Within coleoid cephalopods, octopuses have developed dynamic movements associated with limb hyper-redundancy. As important mesopredators in coastal marine food webs, many species of octopuses are predominantly generalists, feeding on a wide variety of invertebrate and vertebrate prey. Despite their broad diets, few studies have examined the behavioral repertoire of octopus with respect to prey type. We compare how prey type may affect octopus feeding behavior by conducting controlled feeding trials during which we recorded California two-spot octopuses (Octopus bimaculoides, Pickford & McConnaughey, 1949) predating on a sessile prey (Protothaca staminea) and an active prey (Pachygraspus crassipes). We found that prey type had no effect on octopus body orientation, arm choice, nor eye use, but did have a significant influence on the timing events within a feeding sequence, the type of attack used, and attack kinematics. When feeding on clams, octopuses exhibited a shorter latency to move towards prey and make first contact with prey, longer attack decision and prey handling times, and slower attack speed and acceleration compared to when feeding on crabs. Octopuses tended to orient their right eye towards the prey for both first touch and attack during clam trials but during crab trials there was no eye bias. In all trials, eye use appeared to influence arm choice within each prey type. Finally, we report a previously undescribed behavior in the California two-spot octopus: a sinusoidal locomotory pattern that precedes the attack and was observed more commonly for crabs.