Skip to main content Accessibility help
×
Home

Fiddler Crabs Use the Visual Horizon to Distinguish Predators from Conspecifics: A Review of the Evidence

  • John Layne (a1), Michael Land (a2) and Jochen Zeil (a3)

Extract

Male fiddler crabs, Uca pugilator (Crustacea: Decapoda), respond to conspecifics by claw waving, and to predators by freezing or escape. In field experiments it was found that this distinction was not made on the basis of angular size and speed, nor was shape important. The remaining possibilities were either the absolute size of the stimulus, determined from angular size and distance, or the position of the stimulus relative to the horizon. To distinguish between these, a crab was placed in a glass dish, and moved black stimuli on a white background, at a distance of 22 cm. Stimuli below the crab's horizon hardly ever evoked escape. However, identical stimuli partially or wholly above the crab's horizon produced escape responses whose frequency varied with the angular size of the stimulus. Halving the distance of the stimulus showed that it was angular and not absolute size that determines escape frequency; and experiments with a tilted horizon showed that it is the position of the stimulus relative to the eye equator that is important, rather than the geographical horizon itself. It has been concluded that crabs categorize stimuli as dangerous or otherwise by their position relative to the crabs’ visual horizon.

Copyright

References

Hide All
Hagen, H.-O. von, 1962. Freilandstudien zur Sexual- und Forrpflanzungsbiologie von Uca tangeri in Andalusien. Zeitschrift für Morphologie und Ökologie der Tiere, 51, 611725.
Horridge, G.A., 1978. The separation of visual axes in apposition compound eyes. Philosophical Transtransactions of the Royal Society of London B, 285, 159.
Hughes, A., 1977. The topography of vision in mammals of contrasting life-style: comparative optics and retinal organization. In Handbook of sensory physiology. Vol. VII/5. The visual system of vertebrates (ed. F., Crescitelli), pp. 613756. Berlin: Springer Verlag.
Land, M.F. & Layne, J., 1995a. The visual control of behaviour in fiddler crabs. I. Resolution, thresholds and the role of the horizon. Journal of Comparative Physiology, 177 A, 8190.
Land, M.F. & Layne, J., 1995b. The visual control of behaviour in fiddler crabs. II. Tracking control systems in courtship and defence. Journal of Comparative Physiology, 177 A, 91103.
Nalbach, H.-O., 1990. Visually elicited escape in crabs. In Frontiers in crustacean neurobiology (ed. K., Wiese et al.), pp. 165172. Basel: Birkhäuser Verlag. [Advances in Life Sciences.]
Nalbach, H.-O., Zeil, J. & Forzin, L., 1989. Multisensory control of eye-stalk orientation in space: crabs from different habitats rely on different senses. Journal of Comparative Physiology, 165 A, 643649.
Stavenga, D., 1979. Pseudopupils of compound eyes. In Handbook of sensory physiology. Vol. VII/6A. Vision in invertebrates (ed. H., Autrum), pp. 357–139. Berlin: Springer Verlag.
Zeil, J. & Al-Mutairi, M.M., 1996. The variation of resolution and of ommatidial dimensions in the compound eyes of the fiddler crab Uca lactea annulipes (Ocypodidae, Brachyura, Decapoda). Journal of Experimental Biology, 199, 15691577.
Zeil, J., Nalbach, G. & Nalbach, H.-O., 1986. Eyes, eye stalks and the visual world of semi-terrestrial crabs. Journal of Comparative Physiology, 159 A, 801811.
Zeil, J., Nalbach, G. & Nalbach, H.-O., 1989. Spatial vision in a flat world: optical and neural adaptions of arthropods. In Neurobiology of sensory systems (ed. R.N., Singh and N.J., Strausfeld), pp. 123137. New York: Plenum Press.

Fiddler Crabs Use the Visual Horizon to Distinguish Predators from Conspecifics: A Review of the Evidence

  • John Layne (a1), Michael Land (a2) and Jochen Zeil (a3)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed