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Spatial navigation in fiddler crabs: Goal oriented path integration of Uca pugilator

Hong, Luke
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384850701

Abstract Details

2013, MS, University of Cincinnati, Arts and Sciences: Biological Sciences.
The sand fiddler crab (Bosc 1802) Uca pugilator, returns to its burrow using spatial memory of its location created by path integration, a navigational strategy in which an animal measures and sums all locomotion in order to generate a vector leading from the current position to the starting point. It does this without using any directional information external to the body. However, when U. pugilator emerges from its burrow, it forages the surrounding substrate in a non-random fashion, and even does so in complete darkness. This means that, when the crabs emerge from the burrow, at some level they appear to `know'; the directions of previous excursions, and direct subsequent excursions with reference to these. Such a reference can only be obtained using stable and external directional cues. In order to find out what sensory cues U. pugilator uses to establish the required reference direction, I manipulated sensory cues from the burrow structure, from the surrounding substrate, and the ambient magnetic field, in a light-free environment while the crab was inside its burrow, and observed successive foraging excursions. Rotation of the burrow structure alone changes the crab's excursion subsequent to that rotation, while rotation of the substrate surrounding the burrow, and rotation of the magnetic field produced no significant effect. This result supports the idea that U. pugilator measures and integrates movement information, i.e., that it continues path integration, even inside its burrow. Path integration without external cues is more likely to accumulate navigation error than path integration with external cues, since any errors cannot be corrected by an external standard, and so errors are added to an existing vector that contains errors. Errors associated with path integration can be divided into two types: random errors, which are generated by random noise in the measurement or neural calculation, and systematic errors, which are thought to be caused by faulty integration (summing) process. To determine whether U. pugilator commits one or both of these errors, I recorded foraging excursions of crabs in a light-free environment and observed any homing errors. One aspect of the paths, angular range, was significantly greater in excursions which missed the burrow than in those which did not. I also found significant correlations between the magnitude of homing error and all variables tested, with angular range having the highest predictive value. In this paper, I present a complex and unique navigation system employed by U. pugilator and problems the animals face when they explore the environment; returning to a previously visited area and avoiding excessive accumulation of homing error. The results of studies presented here show unique and interesting solutions to the problems faced by navigation system without the use of stable external sensory information.
John Layne, Ph.D. (Committee Chair)
Edwin Griff, Ph.D. (Committee Member)
George Uetz, Ph.D. (Committee Member)
55 p.
Biology
navigation; path integration; systematic error; foraging; Uca pugilator

Recommended Citations

Citations

  • Hong, L. (2013). Spatial navigation in fiddler crabs: Goal oriented path integration of Uca pugilator [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384850701

    APA Style (7th edition)

  • Hong, Luke. Spatial navigation in fiddler crabs: Goal oriented path integration of Uca pugilator. 2013. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384850701.

    MLA Style (8th edition)

  • Hong, Luke. "Spatial navigation in fiddler crabs: Goal oriented path integration of Uca pugilator." Master's thesis, University of Cincinnati, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384850701

    Chicago Manual of Style (17th edition)

ucin1384850701
385
© 2013, some rights reserved.Creative Commons License Spatial navigation in fiddler crabs: Goal oriented path integration of Uca pugilator by Luke Hong is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.