Evaluation of temperament traits and its association with visual lateralisation in oval squid (Sepioteuthis lessoniana)

Many animals feature a left-right asymmetry of brain, morphological structure, and behaviour, namely, lateralisation, which exhibits individual variation within the same population and species. Such variation of lateralisation may be one of mechanisms underlying temperament traits, which is defined by consistent between-individual variation in behaviour across time and/or contexts. Coleoid cephalopods exhibits the individual variation of lateralisation and temperament traits, but it is unrevealed whether there are associations between them. This study investigated whether visual lateralization is associated with temperament traits in oval squid Sepioteuthis lessoniana that exhibits individual variation of visual lateralization. The visual lateralisation was tested for eye preference against prey, predator, and conspecifics. The temperament traits were tested for activity, aggressiveness, exploration-avoidance, shyness-boldness, and sociability. Although activity, aggressiveness, exploration-avoidance, and shyness-boldness showed between-individual consistency, sociability did not show this trend. Moreover, there was not association among temperament traits, suggesting that these traits are independent. The direction of visual lateralisation (left or right) against prey, predator, and conspecifics was positively associated with aggressiveness, exploration-avoidance, and shyness-boldness. The strength of visual lateralisation (stronger or weaker) against prey was positively associated with aggressiveness. We discuss what those associations play a role in oval squid.