Análise comportamental de polvos em cativeiro: um estudo comparativo das espécies Octopus americanus e Octopus insularis

Abstract

Octopuses are cephalopod mollusks that possess a rich behavioral repertoire, which is rare among other invertebrates. Among the more than 300 recognized species of octopus, we highlight Octopus insularis and Octopus americanus, recently differentiated from Octopus vulgaris and native to Brazilian waters. While O. insularis is smaller and inhabits rocky reefs, O. americanus prefers shallow waters up to 200 meters deep. Both species are artisanal and commercial fishing targets throughout their distribution and have been used in research on behavioral ecology and the effects of climate change. However, although these species differ in nature, no previous studies have compared their behavior in captivity, a particularly relevant gap considering their potential application in neuroscience research. In the present study, we first established laboratory infrastructure to house the animals in a controlled environment, a fundamental requirement for conducting behavioral analyses. We then selected three tasks designed to assess novelty aversion. These tests were chosen because neophobia plays a critical role in animal survival and reflects behaviors typically observed in natural habitats. Additionally, variations in neophobia protocols may allow for inferences regarding distinct neurophysiological mechanisms. A total of 38 animals—17 O. americanus and 21 O. insularis—were collected along the coast of Espírito Santo, Brazil. The animals were acclimated and subjected to food, objects, and social neophobia tasks. Sex was determined through histological analysis. Both species adapted to feeding in captivity, although O. americanus adapted more rapidly than O. insularis. Food-related neophobia was more pronounced in O. insularis, as was object-related neophobia, particularly among females. Octopuses are generally known to be asocial, meaning they live in isolation in natural settings. Thus, we anticipated a high degree of social neophobia. Overall, O. americanus appeared to exhibit lower levels of social neophobia than O. insularis; however, statistical differences could not be confirmed due to the high variability in data from this type of test. This pioneering study demonstrates that these two species exhibit different responses in specific behavioral tasks under laboratory conditions. It also establishes baseline conditions for maintaining these species in captivity and for testing fundamental behaviors with sex-based distinctions. These findings enhance our understanding of octopus behavior and contribute to animal welfare, species conservation, and the development of experimental designs involving cephalopods. Moreover, our results underscore the importance of considering sex as a biological variable when investigating the behavior of O. insularis. Future research should explore the neurobiological mechanisms underlying the behaviors described herein.