Intrinsic and extrinsic motivations behind the exploratory behavior of Octopus vulgaris under environmental enrichment and deprivation

Abstract

As global demand for seafood continues to rise, wild finfish stocks are increasingly being depleted. In this context, aquaculture emerges as a pivotal solution, offering a more sustainable alternative to meet consumption demands while alleviating pressure on wild stocks. However, this also raises concerns regarding the welfare and sustainability of farmed aquatic species. Research has shown that animals kept in impoverished environments exhibit more frequent signs of stress, while those under enriched conditions demonstrate enhanced survival, faster growth, improved learning, and increased social interactions. Yet, a higher tendency toward exploration does not necessarily equate to better welfare, as exploratory behavior can be influenced by emotional states and environmental conditions, correlating either with positive cognitive engagement or stress-induced hyperactivity. This dissertation investigates the exploratory behavior of Octopus vulgarisin response to both prey (extrinsic exploration) and novel objects (intrinsic exploration) stimulation under two contrasting rearing/environmental conditions. Using a cross-over experimental design, nine specimens were exposed to a control and a deprived environment (lacking sand, shells, shelters, and rocks) over five days. With daily 20-minute recording sessions, I assessed activity levels, latency to interact with stimuli, interaction duration, and interaction frequency. Results revealed that octopuses in deprived environments exhibited significantly higher activity levels, along with increased interaction frequency. This suggests that environmental deprivation may induce boredom or stress, driving heightened and more rapid engagement with available stimuli. Conversely, those in control environments displayed lower but more selective interactions, potentially reflecting positive emotional states and improved welfare conditions. These findings underscore the profound role of environmental supplementation in improving octopus’ welfare, contributing to the ethical and scientifically informed management of O. vulgaris in controlled settings.