The effects of environmental enrichment and problem-solving on the brain and behavior of Octopus rubescens

Recently the need for enrichment of captive octopus has been proposed. Most studies supporting a need for enrichment of captive octopus are anecdotal and strictly behavioral-based. The effects of environmental enrichment and problem-solving on the brain and behavior of Octopus rubescens were studied. Four groups of octopus were kept in different conditions of environmental enrichment and problem-solving for 50 days. The enriched environment was a tank with a layer of gravel, rocks, plants, and other objects that were rotated every other day to maintain the novelty of the environment. The impoverished environment was an empty tank of the same size. Problem-solving consisted of physical barriers to obtaining food, such as jars with lids. Subsequently, tests of problem-solving ability, exploratory behavior, memory, and a morphological analysis of the brain were completed. There was no difference in problem-solving ability among groups measured by ability to solve a novel puzzle. There also was no difference among groups in exploratory behavior, tested by placing the octopus in a large exploration tank and measuring their activities. Memory was tested by giving the octopus 10 trials in a T-maze, and there were no significant differences in memory ability of the enriched and impoverished octopus. The cross-sectional area and mass of each octopus brain were compared, and there were no significant effects of group. Overall, no significant differences were found among the four groups for problem-solving ability, exploration, memory, or brain measurements, however sample size probably was insufficient