Jumping Spider Optics after Viewing Far and Close Objects

Abstract

By Isaiah Giordullo, Neuroscience and Biology

Advisor: Elke Buschbeck

Awards: Presenter Award: Excellence in Research Communication

Presentation ID: 115

Abstract: The jumping spider, Phidippus audax, is among the most studied arthropods with image-forming eyes in the animal kingdom. Much has been observed about their eye structure and function in the laboratory, but some questions still remain in regard to how spiders use their very large anterior median (AM) eyes to keep their prey in sharp focus at varying distances. Classically, it has been assumed that the jumping spider AM eyes, like other insect eyes, are static, unable to change focus. However, circumstantial observations from the Nelson lab at the University of Canterbury, raises the possibility of a small shift in the way AM eyes are focused when far or close objects are presented. If that is the case, then it is expected that along with a shift in focus, the image magnification of a retinal image would shift between looking close and far. In order to investigate this further we used a custom built micro-ophthalmoscope to take AM eye retinal images immediately after presenting a distantly then closely positioned cricket. Since all parameters were kept constant besides the distance of the cricket, any change in photoreceptor size observed would be due to changes in eye focal length--thus indicating that spiders could have a focusing mechanism in their AM eyes. To quantify potential changes in photoreceptor size, the images taken were overlaid and compared as pixel density in Adobe Photoshop. The analysis revealed no significant changes in pixel density, in line with the classical view that their AM eye is static.