Can preference for crabs in juvenile Octopus maya be modified through early experience with alternative prey?

Previous studies on cephalopod feeding have suggested that predetermined preference for certain prey types can be modified by exposing newly hatched individuals to visual or chemical stimuli (imprinting), or by familiarizing them to feed on prey different from those preferred (associative learning). The aim of our study was to determine whether preference to attack crabs in Octopus maya could be modified by early experience with or without food reinforcement using palaemonid shrimp, a prey octopuses consume readily, but will reject if crabs are available. We conducted experiments on the attack response of juvenile octopuses that had been either exposed to (visual and chemical stimuli for at least 48 h before and after hatching) or had fed only on palaemonids (16 days after hatching). Octopuses were then presented with crabs and palaemonids simultaneously and attacks on either prey were recorded. Control treatments, where octopuses had to choose between two similar alternatives (no choice) were included in order to discriminate between active and passive selection. Results were analysed by means of asymmetrical χ2 contingency tables. Both, octopuses that had only been exposed to stimuli from palaemonids and those that fed on shrimp, selectively attacked crabs when first presented with both alternative prey (χ2=6.09 and χ2=5.01, respectively; both p