Meeting Abstract
Jumping spiders are well known for their extraordinary modular visual systems, which enable complex vision-guided behaviors via a combination of wide-field motion sensitivity and exceptional front-facing visual acuity. However, to what extent jumping spiders see color has remained controversial, with the bulk of evidence suggesting that these spiders have only dichromatic UV-green vision in their principal eyes. This stands in contrast to the broad color palette used in male courtship in several genera, including the genus Habronattus. Dichromatic UV-green vision would be unable to discriminate the long-wavelength colors commonly found in these genera. In addition, our previous work demonstrates a clear role for long-wavelength colors in foraging, learning and mate choice in Habronattus spiders. We characterized the visual sensitivities of H. pyrrithrix to better understand their color vision. Using microspectrophotometry, we determined absorbance spectra of photoreceptors in the tiered principal eye retina, as well as transmittance spectra of optical elements in the light path. We discovered a trichromatic visual system limited to the acute zone of the principal eye retinas, composed of UV, green, and red-sensitive photoreceptors. Red sensitivity is provided by a combination of green photoreceptors and a previously undescribed red filter positioned distally in their light path. Visual modeling indicates that this filter-based trichromacy should enable increased discrimination of male color ornaments by females. Our findings thus reveal a novel mechanism for trichromatic vision in spiders, and may help us to understand the extraordinary radiation of species-specific male color patterns in Habronattus spiders.
