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First published online February 15, 2008
Journal of Experimental Biology 211, 816-823 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.010546
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Vision in the nocturnal wandering spider Leucorchestris arenicola (Araneae: Sparassidae)

Thomas Nørgaard1,*, Dan-Eric Nilsson2, Joh R. Henschel3, Anders Garm2 and Rüdiger Wehner1

1 Department of Zoology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
2 Department of Cell and Organism Biology, University of Lund, Helgonavägen 3, Lund, Sweden
3 Gobabeb Training and Research Centre, PO Box 953, Walvis Bay, Namibia


Figure 1
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  		Fig. 1. (A) Frontal view of an adult male L. arenicola spider showing the eye position on the carapace. (B) Schematic illustration of the eye arrangement. ALE, anterior lateral eye; AME, anterior median eye; PLE, posterior lateral eye; PME, posterior median eye.

 

Figure 2
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  		Fig. 2. (A) Left posterior lateral eye of an adult female L. arenicola showing tapetal glow. (B) Retinal mosaic of a posterior median eye. The individual receptors appear as black dots. (C) Horizontal and longitudinal section through a female AME; (a) rhabdoms, (b) vitreous body, and (c) lens (scale bar, 200 µm).

 

Figure 3
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  		Fig. 3. Histogram illustrating the homing success of spiders with selected pairs of eyes left open in the eye-occlusion experiment. The control group combines untreated and sham-operated animals, i.e. spiders with all eyes functional. The no-eyes group contains spiders with all eyes covered. The LE group had all median eyes covered (AMEs and PMEs disabled), while the ME group had all lateral eyes covered (ALEs and PLEs disabled). The AME group had all eyes but the AMEs covered (ALEs, PMEs and PLEs disabled) and the PME group had the AMEs, ALEs and PLEs covered. The ALE and PLE groups had only the ALEs or PLEs functional, i.e. the AMEs, PMEs and PLEs or the AMEs, PMEs and ALEs were covered. The columns show means + s.e.m. of the number of successful returns made by each spider in the groups (N=number of spiders; normalized data). The schematic illustrations above the columns show which eyes were functional in the experimental group (filled circle indicates covered eye and open circle indicates open eye). All statistical analyses were performed on the absolute values (for details see Results).

 

Figure 4
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  		Fig. 4. (A) Frontal view of the visual fields of the four eyes on the right side of a L. arenicola spider. (B) Lateral view of the right-side visual fields. The equator defines the horizontal plane with the spider exhibiting its typical body posture. The dashed lines mark the boundaries of the ALE visual fields (averages from five spiders, goniometric measurements). The visual fields of the primary eyes are based on histological measurements of the shape of the retina (averages from two spiders).

 

Figure 5
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  		Fig. 5. Spectral sensitivity curves of the four eye pairs. The black lines depict the normalised measured values (means ± s.e.m.). For the AMEs, PMEs and PLEs the peak value is 500 nm. In the ALEs the peak lies at 530 nm. The grey lines show theoretical spectral sensitivity curves for single photopigments fitted to the measured values using the least sum of squares method. The peaks of the theoretical curves lie at 525 nm (AME), 541 nm (ALE), 523 nm (PME) and 529 nm (PLE). The measurements were done on four adult spiders (one male and three females).

 

Figure 6
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  		Fig. 6. Scatter plot showing the distribution of the 57 stance durations (black dots) as a function of relative ambient light intensity (for details see Materials and methods). The crosses show the five outliers excluded from the statistical calculation. The trend line shows the relationship between stance duration and relative ambient light intensity (y=–0.0025x + 0.7779, Spearman r=–0.3148).

 




© The Company of Biologists Ltd 2008