The wolf spider Lycosa tarantula returns home by means of path integration. Previous studies demonstrated: (i) that the angular component of the outbound run is measured using a polarized-light compass associated with the anterior median eyes; (ii) changes in direction of the substratum are detected by the anterior lateral eyes (ALEs); and (iii) in relation to the linear component of the outbound run, an increase of optic flow, in either the lateral or ventral fields of view, caused spiders to search for the burrow at a point nearer to the goal. However, the role of the secondary eyes [ALEs, posterior lateral eyes (PLEs) and posterior median eyes (PMEs)] in the perception of this optic flow and the importance of them for gauging the distance walked is still unknown. In this study, lateral or ventral gratings of wavelength λ=1 cm were used, with two groups of spiders in each setup: (1) PLEs+PMEs covered and (2) ALEs covered. The largest reduction in the distance walked to return to the burrow was observed with the ventral grating/ALEs covered. These results show the importance of the previously neglected ALEs for the visual behavior of these spiders. The possibility of gathering information for locomotion from the three pairs of secondary eyes in the mushroom bodies is discussed.
The authors declare no competing or financial interests.
J.O.-E. conceived the study, designed and carried out the experiments, collected the data, carried out interim data analysis, and guided the interpretation of findings and the development of the manuscript, both in drafting and in review. M.A.R. contributed to the design of the experiments, carried out statistical data analysis, participated in the drafting and development of the manuscript, participated in the interpretation of data and study results, and critically reviewed the manuscript. Both authors read and approved the final manuscript.
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
- Received July 12, 2016.
- Accepted October 22, 2016.
- © 2017. Published by The Company of Biologists Ltd