Abstract
Many animals use the sun's polarization pattern to orientate, but the dung beetle Scarabaeus zambesianus is the only animal so far known to orientate using the million times dimmer polarization pattern of the moonlit sky. We demonstrate the relative roles of the moon and the nocturnal polarized-light pattern for orientation. We find that artificially changing the position of the moon, or hiding the moon's disc from the beetle's field of view, generally did not influence its orientation performance. We thus conclude that the moon does not serve as the primary cue for orientation. The effective cue is the polarization pattern formed around the moon, which is more reliable for orientation. Polarization sensitivity ratios in two photoreceptors in the dorsal eye were found to be 7.7 and 12.9, similar to values recorded in diurnal navigators. These results agree with earlier results suggesting that the detection and analysis of polarized skylight is similar in diurnal and nocturnal insects.
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Selected References
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- Blum M., Labhart T. Photoreceptor visual fields, ommatidial array, and receptor axon projections in the polarisation-sensitive dorsal rim area of the cricket compound eye. J Comp Physiol A. 2000 Feb;186(2):119–128. doi: 10.1007/s003590050012. [DOI] [PubMed] [Google Scholar]
- Byrne Marcus, Dacke Marie, Nordström Peter, Scholtz Clarke, Warrant Eric. Visual cues used by ball-rolling dung beetles for orientation. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2003 May 1;189(6):411–418. doi: 10.1007/s00359-003-0415-1. [DOI] [PubMed] [Google Scholar]
- Dacke M., Nordström P., Scholtz C. H., Warrant E. J. A specialized dorsal rim area for polarized light detection in the compound eye of the scarab beetle Pachysoma striatum. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2002 Mar 13;188(3):211–216. doi: 10.1007/s00359-002-0295-9. [DOI] [PubMed] [Google Scholar]
- Dacke Marie, Nilsson Dan-Eric, Scholtz Clarke H., Byrne Marcus, Warrant Eric J. Animal behaviour: insect orientation to polarized moonlight. Nature. 2003 Jul 3;424(6944):33–33. doi: 10.1038/424033a. [DOI] [PubMed] [Google Scholar]
- Dacke Marie, Nordström Peter, Scholtz Clarke H. Twilight orientation to polarised light in the crepuscular dung beetle Scarabaeus zambesianus. J Exp Biol. 2003 May;206(Pt 9):1535–1543. doi: 10.1242/jeb.00289. [DOI] [PubMed] [Google Scholar]
- Freake MJ. Evidence for orientation using the e-vector direction of polarised light in the sleepy lizard tiliqua rugosa . J Exp Biol. 1999 May;202(Pt 9):1159–1166. doi: 10.1242/jeb.202.9.1159. [DOI] [PubMed] [Google Scholar]
- Kerfoot W. B. The lunar periodicity of Sphecodogastra texana, a nocturnal bee (Hymenoptera: Halictidae). Anim Behav. 1967 Oct;15(4):479–486. doi: 10.1016/0003-3472(67)90047-4. [DOI] [PubMed] [Google Scholar]
- Labhart T., Meyer E. P. Detectors for polarized skylight in insects: a survey of ommatidial specializations in the dorsal rim area of the compound eye. Microsc Res Tech. 1999 Dec 15;47(6):368–379. doi: 10.1002/(SICI)1097-0029(19991215)47:6<368::AID-JEMT2>3.0.CO;2-Q. [DOI] [PubMed] [Google Scholar]
- Labhart T., Petzold J., Helbling H. Spatial integration in polarization-sensitive interneurones of crickets: a survey of evidence, mechanisms and benefits. J Exp Biol. 2001 Jul;204(Pt 14):2423–2430. doi: 10.1242/jeb.204.14.2423. [DOI] [PubMed] [Google Scholar]
- Ugolini Alberto, Fantini Tiziana, Innocenti Riccardo. Orientation at night: an innate moon compass in sandhoppers (Amphipoda: Talitridae). Proc Biol Sci. 2003 Feb 7;270(1512):279–281. doi: 10.1098/rspb.2002.2221. [DOI] [PMC free article] [PubMed] [Google Scholar]