P1.48 Wednesday, Jan. 4 Visual Cues for Burrow Surveillance in Fiddler Crabs KIM, D.*; YU, S.-E.; Yonsei University, Seoul email@example.com
Fiddler crabs show a surveillance behavior against a potential intruder to protect their burrow. In the vicinity of the intruder, they rush back to the burrow to keep its possesion. Recent work by biologists shows that crabs combine visual information and path integration. They can always do path integration to return to the burrow after exploring for food, indicating that crabs estimate the distance to the burrow from a far-away region. Additionally, a matched filter with the azimuth and elevation position of the intruder in the retinal view can draw the visual geometry of the environment. It is believed that crabs combine the visual information and path integration for the surveillance. Several visual cues including the position of an intruder, the apparent size and the speed of the intruder in the retinal map are available. To respond to the intruder appropriately, crabs should estimate the relative location of the intruder to the burrow. Here, we propose that the movement speed estimation of an intruder using the variation of size and transition of the intruder's movement in the retinal view can build a spatial geometry for the movement of the potential intruder. It can provide the distance and direction of the intruder from the burrow entrance. In our modeling experiments, it is shown that the target speed estimation can be another visual cue to judge the intruder-burrow distance. It suggests a hypothesis that crabs might use several different cues, azimuth and elevation of the intruder in the retinal view, the image size variation, and the movement speed in the retinal view.