Filtering system explains jumping spiders’ full color vision

Los Angeles Times : Many species of jumping spiders, such as Habronattus pyrrithrix, are brightly colored but their eyes have photoreceptors only for UV and green light. Why the spiders would have evolved coloring that they couldn’t see was unclear. Now Daniel Zurek of the University of Pittsburgh in Pennsylvania and his colleagues have determined that H. pyrrithrix can, in fact, see the coloring because its eyes contain filters over some of the green pigment photoreceptors. The discovery also helps to explain the unusual scanning movement of the spiders’ eyes. The area of the eye that has the filters is so small that the field of vision is very narrow. The scanning greatly expands the field of view. Zurek’s team found that the pigment filter is common to many of the Habronattus spiders, which may explain the success and diversity of the species.