Adaptive strategies of animal behaviors based on spontaneous self-motions

Abstract

Creatures may exhibit spontaneous self-motions in independ ent on environmental stimuli. Spontaneous self-motions gen erate noises that might disturb the accuracy of environmental responsive behaviors or directional movements, and thus functions of the spontaneous self-motions in animal behaviors have not been studied. Recently, several reports showed, how ever, that spontaneous self-motions specify the efficiency of animal behaviors, suggesting that spontaneous self-motion is a platform that serves for adaptive outcomes of animal behav iors. The freshwater planarian Dugesia japonica belongs to an evolutionarily early group possessing paired eyes with a simple architecture and displays robust photo-response eva sive behavior through neural wiring between the eyes and a simple-structured but stunning brain. More recently, it was demonstrated that spontaneous wigwag self-motion of the head of planarians breaks the symmetry of the eyes’ inputs during photo-orientation behavior. Notably, the angle and fre quency of the spontaneous wigwag self-motion were opti mized and strongly correlated with the angle of the binocular field for ensuring accurate photo-orientation behavior. Furthermore, the angle and frequency of the spontaneous wigwag self-motion were optimized for other adaptive behav iors, such as hiding in a concave space on a stone, even in the absence of environmental cues. Collectively, these insights suggest that spontaneous self-motion ensures the movement in the precise direction for enabling the simple, but efficient and robust outcomes of multiple behaviors.