Journal of Comparative Physiology A

, Volume 177, Issue 1, pp 91–103

The visual control of behaviour in fiddler crabs

II. Tracking control systems in courtship and defence
  • Michael Land
  • John Layne
Original Paper

DOI: 10.1007/BF00243401

Cite this article as:
Land, M. & Layne, J. J Comp Physiol A (1995) 177: 91. doi:10.1007/BF00243401


Male fiddler crabs (Uca pugilator Bosc) have visual control systems that enable them to track other crabs in front or behind, and to keep potential predators to the side, where escape is easiest. The system for tracking conspecifics appears to be double, with a low-gain velocity-sensitive mechanism operating over about a 90° range, backed up by a position-sensitive mechanism at the ends of this range which is responsible for recentring the target. This system has separate front and rear ranges, with a gap in the direction of the claw. The crabs separately fixate the burrow entrance, keeping it in the direction opposite the claw. Predator evasion employs two systems simultaneously. An openloop mechanism directs the crab's translatory movements directly away from the stimulus, and a rotational mechanism using continuous feedback turns the crab so that the stimulus is kept at near 90° to the body axis. Both systems are sensitive to the angular position of the stimulus, not its velocity. Eye movements have little or no role in object tracking. An attempt is made to list Uca's known visual control systems.

Key words

Crustacea Uca Vision Orientation Control systems 

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • Michael Land
    • 2
  • John Layne
    • 2
  1. 1.School of Biological SciencesUniversity of SussexBrightonUK
  2. 2.Duke University Marine LaboratoryPivers Island, BeaufortUSA