Directional Cues Used by Sand Fiddler Crabs During Spatial Navigation

Abstract

Record ID: 89

Award(s): Excellence in Undergraduate Research Mentorship

Program Affiliation: NA

Presentation Type: Poster

Abstract: This research investigates the navigation mechanisms of Atlantic sand fiddler crabs as they return to their burrows after foraging. The study aims to discern whether these crabs rely on internal cues (e.g., self-generated visual motion, limb movements, acceleration) or external cues (e.g., visual landmarks, sun, sky polarization) when finding their way home to their burrow. For example, an external cue that animals commonly use is the sun or other physical entity as a recognizable landmark when homing. An internal cue could be the bodily movements of the organism, which can be measured by sensory systems such as proprioception. To address this, we placed rotatable disks amongst fiddler crab burrows. When a crab reached a disk during an excursion, the experimenter pulled a line to turn the disk. This rotated the crab's body, and thus passively changed their orientation relative to home. They were video-recorded and their routes were tracked using custom software (MATLAB). It was found that the crabs' homing direction deviated from their burrow direction by an amount very similar to the amount they were rotated. This suggests a dependence on internal cues for navigation, and not external cues. If external cues had been the dominant cues for the fiddler crabs' navigation mechanism, a bodily rotation wouldn't significantly impact homing direction and they would have returned home without the observed error. This research contributes insights into sensory physiology, comparative biology, and neuroscience, shedding light on the intricacies of navigation behavior.