Does size affect orientation using celestial cues?
Insects are well known to orient using celestial cues. The pattern of polarised skylight is the dominant celestial compass information that insects use, which they detect using a specialised set of ommatidia. The number of ommatidia decreases with body size, and it is unknown how this reduction in the number of ommatidia affects the precision of orienting using celestial cues. We investigated this in eight different ant species that had varying numbers of ommatidia. We captured ants returning home, displaced them to an unfamiliar location and measured their precision in determining heading direction using celestial cues. The heading direction of the ants measured at a fixed distance from the release and also at a distance scaled to their body size was not correlated with the number of ommatidia. However, both the path straightness and walking speed were lower in smaller ants indicating the ability to orient at a finer scale was affected by miniaturisation.
KeywordsMiniaturisation Polarisation vision Dorsal rim area Compass cues
We thank Jochen Zeil for hosting us at the ANU and the MQ neuroethology group and two reviewers for their helpful comments. The research was supported by the Australian Research Council (FT140100221 and DP150101172) and International Macquarie University Research Excellence Scholarship (iMQRES 2015141).
Compliance with ethical standards
The data are provided in the electronic supplementary material and https://ecologicalneuroscience.files.wordpress.com/2018/03/displ_data_codes.zip.
Conflict of interest
We have no competing interests.
Research on ants does not require animal ethical approval in Australia.
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