Wall-following behavior: Its ultimate and proximate explanations, prevalence, and implications

Abstract

Wall-following behavior is the movement along a wall exhibited by various animals. Itis a conserved behavior among taxa, from unicellular organisms to humans, prone toselection pressure, and it is energetically cheap since it provides a homogenous trailand can help animals to follow the shortest distance between two points. There arethree sets of explanations for this behavior. The first is that it is a defensive behaviormeant to lead the animal to shelter or reduce predation risk, and which, at least invertebrates, is a proxy of anxiety. The second explanation suggests it is an exploratorybehavior, helping an animal either to exit an enclosed space or to orient in a novel(unfamiliar) environment, especially when vision is limited. As novel environmentsoften induce stress, these two explanations are not mutually exclusive. Finally, the wallitself may offer some desired biotic or abiotic conditions, such as a higher preyavailability moving along it or favorable microclimate conditions. (e.g., more in smaller arenas), shape, and illumination level. Standardization of itsmeasurement is required to facilitate comparison among studies and species. Thetiming of examination plays a role too: Wall following often changes along developmentand with aging. Generally, females follow walls more often than do males.Furthermore, certain conditions experienced at a young age affect wall-followinglater, so the behavioral changes may be long-lasting. Wall following is correlated witha few other behaviors, such as a negative correlation with phototaxis and activity. Weend our review by presenting some future research directions, such as examiningwall-following behavior in predator-prey systems, examining whether and when wallfollowingis adaptive, and studying it in the context of urban ecology. Finally, there isa need to examine how common this behavior is in the wild as most studies havebeen conducted in the lab.