Focus on Jumping Spiders

Jumping spiders on the hunt must accurately judge the distance to their prey, but they do not use the usual methods of depth perception. Most animals gauge distance by either adjusting the focal length of their lenses or moving their heads to observe parallax motion. However, Nagata et al. show that jumping spiders use "image defocus" to judge distance. In image defocus, an unfocused image and focused image are compared within the same eye. When the researchers analyzed the layers of the jumping spiders' retinas, they found a specialized layer of green pigment that captures a defocused version of what the spider is looking at. This reliance on green light is shown in the accompanying video where the jumping spiders stalk their prey successfully under normal and green light conditions but miss their targets when bathed in red light alone. Science (www.sciencemag.org) is the world's leading journal of original scientific research, global news, and commentary. For more original videos, check out the Science Video Portal (video.sciencemag.org).