Examination of Homing Behaviors in Two Species of Crayfish Following Translational Displacements

Crayfish have been model systems for examining complex behaviors and the underlying neural mechanisms that guide these behaviors. While spatial learning has been examined in a subset of crayfish species, homing behaviors remained largely unexamined. Here we examined homing behavior following translational displacements in a primary burrowing (Creaserinus fodiens) and tertiary burrowing species (Faxonius rusticus). Individuals of both species were placed in an arena with artificial burrows embedded within the arena floor. The arena floor was fitted with a panel, which served as a treadmill belt to allow for translational displacement. Individuals were displaced after they had left the burrows. The movement pathways of displaced crayfish were compared with those in two control groups, one which underwent no displacement and the second in which the treadmill belt was displaced but returned to its original position almost immediately. Homing success for displaced individuals of both species was considerably reduced in comparison to the control groups. Moreover, displaced primary burrowers had significantly lower homing success in comparison to displaced tertiary burrowers. Primary burrowers exhibited greater homing error and significantly impaired homing behaviors compared with tertiary burrowers. Furthermore, heading angles in displaced groups (of both species) were significantly higher than the control group of both species. Species-specific differences in homing success and homing error indicate that primary burrowers were more negatively impacted by translational displacements. These homing differences indicate that these two species of crayfish have differing homing strategies.